CVE-2026-89538

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89538", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.721Z", "datePublished": "2026-09-11T19:44:15.953Z", "dateUpdated": "2026-10-19T08:48:29.976Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:29.976Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject krb5 v2 wrap tokens with oversized ec field\n\ngss_krb5_unwrap_v2() sets buf->len to a logical\nlength, which can be much smaller than head[0].iov_len\n(the allocated receive-page capacity). It then calls\nxdr_buf_trim() with a trim length derived from the 16-bit\n\"extra count\" (ec) field in the Kerberos v2 token header.\n\nThe ec field is authenticated by the post-decrypt memcmp()\nagainst the encrypted header copy, so a randomly-mutated\nvalue is rejected. However, any peer holding a valid GSS\ncontext can legitimately encrypt a token whose ec exceeds\nthe plaintext length. Per RFC 4121, such a token is\nstructurally malformed.\n\nAlthough xdr_buf_trim() now clamps the buf->len subtraction\nto avoid unsigned underflow, the buffer is still left in a\nsemantically invalid state (zero length, inconsistent iov\nlengths) when ec is oversized.\n\nReject these tokens before calling xdr_buf_trim(), giving\ncallers a well-defined GSS_S_DEFECTIVE_TOKEN error and\nkeeping the xdr_buf internally consistent. The wrapped blob\nbegins at a nonzero offset -- both callers pass len as\noffset + opaque_len -- so buf->len still counts the offset\nbytes that precede the blob. Compare the trim length\nagainst the remaining wrapped segment, buf->len - offset,\nrather than the whole buffer; comparing against buf->len\nalone leaves an offset-wide window in which an oversized ec\npasses the test and xdr_buf_trim() cuts into the bytes ahead\nof the blob."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL"}, "scenarios": [{"lang": "en", "value": "AV:N - gss_krb5_unwrap_v2() is reached from nfsd RPCSEC_GSS privacy unwrap on TCP/2049 and from the NFS client's gss_unwrap_resp_priv() on every krb5p reply, so a remote NFS peer delivers the oversized-ec wrap token over the network.\nAC:L - A peer holding the GSS session keys can encrypt a RFC 4121 wrap token whose authenticated ec exceeds the plaintext; decrypt and the header memcmp succeed, then xdr_buf_trim() runs with that chosen length and no race or layout outside attacker control.\nPR:N - A malicious or compromised NFS server that already shares a krb5p GSS context needs no account or capability on the victim client; ordinary krb5p replies and NFSv4.0 GSS callbacks are processed without local privileges on that host.\nUI:N - Once a krb5p NFS mount exists, the client unwraps every privacy-protected reply and NFSv4.0 GSS callback with no further mount, click, or open; idle revalidations and server-driven callbacks are sufficient.\nS:U - The corrupted xdr_buf and subsequent XDR decode and shift run in the host kernel that processed the RPC and do not cross a VM, IOMMU, or sandbox boundary.\nC:H - An oversized ec makes xdr_buf_trim() underflow buf->len toward UINT_MAX, so later xdr_read_pages/xdr_shrink_bufhead use that length as a copy bound and read far past the receive buffer into adjacent kernel memory.\nI:H - xdr_shrink_bufhead() then calls xdr_buf_head_shift_right() with a near-UINT_MAX length derived from the wrapped buf->len, an out-of-bounds write into kernel memory that can be used for control-flow hijacking.\nA:H - Those unbounded XDR copies and the inconsistent xdr_buf (wrapped or zero length versus iov_lens) oops or panic nfsd or the NFS client, and the peer can repeat the request at will."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sunrpc/auth_gss/gss_krb5_wrap.c"], "versions": [{"version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "ac9efc29346b6942e71f0e24a3178a9121330fab", "status": "affected", "versionType": "git"}, {"version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "b5746095b59f4d11f39f08751d36bbdfd1e5deac", "status": "affected", "versionType": "git"}, {"version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "9fc6d6e6db49ab55208d5dd1c424c1d0d9aa7296", "status": "affected", "versionType": "git"}, {"version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "4abb44a29bb515df6f49123848765c70fc9b5021", "status": "affected", "versionType": "git"}, {"version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "dfcd81ab45613d45996fbf483d4ef54b0ec90ab9", "status": "affected", "versionType": "git"}, {"version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "1f9856af065b6158271687e9788407b9573fd16f", "status": "affected", "versionType": "git"}, {"version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "880effc943ed82d6811f272ed3307c222b40f4d6", "status": "affected", "versionType": "git"}, {"version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "ad484748eec0a66eac0f13ab53b3fbedb7333c91", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sunrpc/auth_gss/gss_krb5_wrap.c"], "versions": [{"version": "3.13", "status": "affected"}, {"version": "0", "lessThan": "3.13", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "5.10.270"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "5.15.221"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.1.188"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.6.157"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.12.109"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/ac9efc29346b6942e71f0e24a3178a9121330fab"}, {"url": "https://git.kernel.org/stable/c/b5746095b59f4d11f39f08751d36bbdfd1e5deac"}, {"url": "https://git.kernel.org/stable/c/9fc6d6e6db49ab55208d5dd1c424c1d0d9aa7296"}, {"url": "https://git.kernel.org/stable/c/4abb44a29bb515df6f49123848765c70fc9b5021"}, {"url": "https://git.kernel.org/stable/c/dfcd81ab45613d45996fbf483d4ef54b0ec90ab9"}, {"url": "https://git.kernel.org/stable/c/1f9856af065b6158271687e9788407b9573fd16f"}, {"url": "https://git.kernel.org/stable/c/880effc943ed82d6811f272ed3307c222b40f4d6"}, {"url": "https://git.kernel.org/stable/c/ad484748eec0a66eac0f13ab53b3fbedb7333c91"}], "title": "SUNRPC: Reject krb5 v2 wrap tokens with oversized ec field", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-89538", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T19:23:19.852732Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:41.901Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-89538", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T19:23:19.852732Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:23:20.771Z"}}], "cna": {"title": "SUNRPC: Reject krb5 v2 wrap tokens with oversized ec field", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 9.8, "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:N - gss_krb5_unwrap_v2() is reached from nfsd RPCSEC_GSS privacy unwrap on TCP/2049 and from the NFS client's gss_unwrap_resp_priv() on every krb5p reply, so a remote NFS peer delivers the oversized-ec wrap token over the network.\nAC:L - A peer holding the GSS session keys can encrypt a RFC 4121 wrap token whose authenticated ec exceeds the plaintext; decrypt and the header memcmp succeed, then xdr_buf_trim() runs with that chosen length and no race or layout outside attacker control.\nPR:N - A malicious or compromised NFS server that already shares a krb5p GSS context needs no account or capability on the victim client; ordinary krb5p replies and NFSv4.0 GSS callbacks are processed without local privileges on that host.\nUI:N - Once a krb5p NFS mount exists, the client unwraps every privacy-protected reply and NFSv4.0 GSS callback with no further mount, click, or open; idle revalidations and server-driven callbacks are sufficient.\nS:U - The corrupted xdr_buf and subsequent XDR decode and shift run in the host kernel that processed the RPC and do not cross a VM, IOMMU, or sandbox boundary.\nC:H - An oversized ec makes xdr_buf_trim() underflow buf->len toward UINT_MAX, so later xdr_read_pages/xdr_shrink_bufhead use that length as a copy bound and read far past the receive buffer into adjacent kernel memory.\nI:H - xdr_shrink_bufhead() then calls xdr_buf_head_shift_right() with a near-UINT_MAX length derived from the wrapped buf->len, an out-of-bounds write into kernel memory that can be used for control-flow hijacking.\nA:H - Those unbounded XDR copies and the inconsistent xdr_buf (wrapped or zero length versus iov_lens) oops or panic nfsd or the NFS client, and the peer can repeat the request at will."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "ac9efc29346b6942e71f0e24a3178a9121330fab", "versionType": "git"}, {"status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "b5746095b59f4d11f39f08751d36bbdfd1e5deac", "versionType": "git"}, {"status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "9fc6d6e6db49ab55208d5dd1c424c1d0d9aa7296", "versionType": "git"}, {"status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "4abb44a29bb515df6f49123848765c70fc9b5021", "versionType": "git"}, {"status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "dfcd81ab45613d45996fbf483d4ef54b0ec90ab9", "versionType": "git"}, {"status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "1f9856af065b6158271687e9788407b9573fd16f", "versionType": "git"}, {"status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "880effc943ed82d6811f272ed3307c222b40f4d6", "versionType": "git"}, {"status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "lessThan": "ad484748eec0a66eac0f13ab53b3fbedb7333c91", "versionType": "git"}], "programFiles": ["net/sunrpc/auth_gss/gss_krb5_wrap.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "3.13"}, {"status": "unaffected", "version": "0", "lessThan": "3.13", "versionType": "semver"}, {"status": "unaffected", "version": "5.10.270", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.221", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.188", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.157", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.109", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.50", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.2.4", "versionType": "semver", "lessThanOrEqual": "7.2.*"}, {"status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/sunrpc/auth_gss/gss_krb5_wrap.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/ac9efc29346b6942e71f0e24a3178a9121330fab"}, {"url": "https://git.kernel.org/stable/c/b5746095b59f4d11f39f08751d36bbdfd1e5deac"}, {"url": "https://git.kernel.org/stable/c/9fc6d6e6db49ab55208d5dd1c424c1d0d9aa7296"}, {"url": "https://git.kernel.org/stable/c/4abb44a29bb515df6f49123848765c70fc9b5021"}, {"url": "https://git.kernel.org/stable/c/dfcd81ab45613d45996fbf483d4ef54b0ec90ab9"}, {"url": "https://git.kernel.org/stable/c/1f9856af065b6158271687e9788407b9573fd16f"}, {"url": "https://git.kernel.org/stable/c/880effc943ed82d6811f272ed3307c222b40f4d6"}, {"url": "https://git.kernel.org/stable/c/ad484748eec0a66eac0f13ab53b3fbedb7333c91"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject krb5 v2 wrap tokens with oversized ec field\n\ngss_krb5_unwrap_v2() sets buf->len to a logical\nlength, which can be much smaller than head[0].iov_len\n(the allocated receive-page capacity). It then calls\nxdr_buf_trim() with a trim length derived from the 16-bit\n\"extra count\" (ec) field in the Kerberos v2 token header.\n\nThe ec field is authenticated by the post-decrypt memcmp()\nagainst the encrypted header copy, so a randomly-mutated\nvalue is rejected. However, any peer holding a valid GSS\ncontext can legitimately encrypt a token whose ec exceeds\nthe plaintext length. Per RFC 4121, such a token is\nstructurally malformed.\n\nAlthough xdr_buf_trim() now clamps the buf->len subtraction\nto avoid unsigned underflow, the buffer is still left in a\nsemantically invalid state (zero length, inconsistent iov\nlengths) when ec is oversized.\n\nReject these tokens before calling xdr_buf_trim(), giving\ncallers a well-defined GSS_S_DEFECTIVE_TOKEN error and\nkeeping the xdr_buf internally consistent. The wrapped blob\nbegins at a nonzero offset -- both callers pass len as\noffset + opaque_len -- so buf->len still counts the offset\nbytes that precede the blob. Compare the trim length\nagainst the remaining wrapped segment, buf->len - offset,\nrather than the whole buffer; comparing against buf->len\nalone leaves an offset-wide window in which an oversized ec\npasses the test and xdr_buf_trim() cuts into the bytes ahead\nof the blob."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.270", "versionStartIncluding": "3.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.221", "versionStartIncluding": "3.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.188", "versionStartIncluding": "3.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.157", "versionStartIncluding": "3.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.109", "versionStartIncluding": "3.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.50", "versionStartIncluding": "3.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.2.4", "versionStartIncluding": "3.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.3", "versionStartIncluding": "3.13"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:29.976Z"}}}, "cveMetadata": {"cveId": "CVE-2026-89538", "state": "PUBLISHED", "dateUpdated": "2026-10-19T08:48:29.976Z", "dateReserved": "2026-09-11T19:38:34.721Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-09-11T19:44:15.953Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/sunrpc/auth_gss/gss_krb5_wrap.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "ac9efc29346b6942e71f0e24a3178a9121330fab", "status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "versionType": "git"}, {"lessThan": "b5746095b59f4d11f39f08751d36bbdfd1e5deac", "status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "versionType": "git"}, {"lessThan": "9fc6d6e6db49ab55208d5dd1c424c1d0d9aa7296", "status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "versionType": "git"}, {"lessThan": "4abb44a29bb515df6f49123848765c70fc9b5021", "status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "versionType": "git"}, {"lessThan": "dfcd81ab45613d45996fbf483d4ef54b0ec90ab9", "status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "versionType": "git"}, {"lessThan": "1f9856af065b6158271687e9788407b9573fd16f", "status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "versionType": "git"}, {"lessThan": "880effc943ed82d6811f272ed3307c222b40f4d6", "status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "versionType": "git"}, {"lessThan": "ad484748eec0a66eac0f13ab53b3fbedb7333c91", "status": "affected", "version": "cf4c024b908353fcc48309374d39e3399d67dfd1", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/sunrpc/auth_gss/gss_krb5_wrap.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "3.13"}, {"lessThan": "3.13", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.270", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.221", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.188", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.157", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.109", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.50", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject krb5 v2 wrap tokens with oversized ec field\n\ngss_krb5_unwrap_v2() sets buf->len to a logical\nlength, which can be much smaller than head[0].iov_len\n(the allocated receive-page capacity). It then calls\nxdr_buf_trim() with a trim length derived from the 16-bit\n\"extra count\" (ec) field in the Kerberos v2 token header.\n\nThe ec field is authenticated by the post-decrypt memcmp()\nagainst the encrypted header copy, so a randomly-mutated\nvalue is rejected. However, any peer holding a valid GSS\ncontext can legitimately encrypt a token whose ec exceeds\nthe plaintext length. Per RFC 4121, such a token is\nstructurally malformed.\n\nAlthough xdr_buf_trim() now clamps the buf->len subtraction\nto avoid unsigned underflow, the buffer is still left in a\nsemantically invalid state (zero length, inconsistent iov\nlengths) when ec is oversized.\n\nReject these tokens before calling xdr_buf_trim(), giving\ncallers a well-defined GSS_S_DEFECTIVE_TOKEN error and\nkeeping the xdr_buf internally consistent. The wrapped blob\nbegins at a nonzero offset -- both callers pass len as\noffset + opaque_len -- so buf->len still counts the offset\nbytes that precede the blob. Compare the trim length\nagainst the remaining wrapped segment, buf->len - offset,\nrather than the whole buffer; comparing against buf->len\nalone leaves an offset-wide window in which an oversized ec\npasses the test and xdr_buf_trim() cuts into the bytes ahead\nof the blob."}], "id": "CVE-2026-89538", "lastModified": "2026-10-19T09:17:48.573", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-89538", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T19:23:19.852732Z", "version": "2.0.3"}}]}, "published": "2026-09-11T20:19:36.850", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1f9856af065b6158271687e9788407b9573fd16f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4abb44a29bb515df6f49123848765c70fc9b5021"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/880effc943ed82d6811f272ed3307c222b40f4d6"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/9fc6d6e6db49ab55208d5dd1c424c1d0d9aa7296"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/ac9efc29346b6942e71f0e24a3178a9121330fab"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/ad484748eec0a66eac0f13ab53b3fbedb7333c91"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b5746095b59f4d11f39f08751d36bbdfd1e5deac"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/dfcd81ab45613d45996fbf483d4ef54b0ec90ab9"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel: SUNRPC vulnerability in Kerberos v2 token processing", "id": "2532114", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532114"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-131", "details": ["A flaw was found in the Linux kernel's Server Unix Remote Procedure Call (SUNRPC) component. A remote attacker, with a valid Generic Security Service (GSS) context, could send a specially crafted Kerberos v2 wrap token with an oversized \"extra count\" (ec) field. This improper handling of malformed tokens could lead to the buffer being left in a semantically invalid state, potentially causing a denial of service or other unpredictable behavior within the system."], "name": "CVE-2026-89538", "public_date": "2026-09-11T19:44:15Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89538\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89538\nhttps://git.kernel.org/stable/c/1f9856af065b6158271687e9788407b9573fd16f\nhttps://git.kernel.org/stable/c/880effc943ed82d6811f272ed3307c222b40f4d6\nhttps://git.kernel.org/stable/c/ad484748eec0a66eac0f13ab53b3fbedb7333c91\nhttps://git.kernel.org/stable/c/dfcd81ab45613d45996fbf483d4ef54b0ec90ab9"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[cf4c024b908353fcc48309374d39e3399d67dfd1,dfcd81ab45613d45996fbf483d4ef54b0ec90ab9)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[cf4c024b908353fcc48309374d39e3399d67dfd1,1f9856af065b6158271687e9788407b9573fd16f)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[cf4c024b908353fcc48309374d39e3399d67dfd1,880effc943ed82d6811f272ed3307c222b40f4d6)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[cf4c024b908353fcc48309374d39e3399d67dfd1,ad484748eec0a66eac0f13ab53b3fbedb7333c91)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "3.13"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,3.13)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.109,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.50,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.4,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-12T03:30:08.482303+00:00", "updated": "2026-09-15T22:15:17.694978+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}