CVE-2026-89641

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89641", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.740Z", "datePublished": "2026-09-11T19:45:34.036Z", "dateUpdated": "2026-10-19T08:50:13.143Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:50:13.143Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size()\n\nWhen the else branch of cifs_file_set_size() finds a writable file handle\nvia find_writable_file(), it borrows tcon and server from the handle's\ntlink, attempts the handle-based set_file_size() RPC, and then releases\nthe handle with cifsFileInfo_put().\n\nIf set_file_size() fails, execution falls through to the path-based\nfallback, which reuses the borrowed tcon and server under the\n\"if (tcon == NULL)\" guard. Since tcon is not NULL at that point, the\nguard is skipped. If cifsFileInfo_put() dropped the last reference on a\ntlink that was already removed from the tlink tree (TCON_LINK_IN_TREE\ncleared, as happens during reconnection or session teardown),\ncifs_put_tlink() will have freed tcon; the subsequent set_path_size()\ncall is then a use-after-free.\n\nSetting tcon = NULL after cifsFileInfo_put() causes the existing guard\nto take the cifs_sb_tlink() path, which acquires a fresh reference for\nthe path-based operation or fails cleanly if the session is gone."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The UAF is in the CIFS client setattr path (fs/smb/client/inode.c cifs_file_set_size), reached only via local VFS truncate/setattr on a mounted SMB share (sys_truncate \u2192 vfs_truncate \u2192 notify_change \u2192 cifs_setattr), not via ksmbd or unsolicited SMB receive processing.\nAC:L - A local attacker controls both sides: keep a writable handle open, issue truncate(2) to hit the find_writable_file() else branch, fail handle-based set_file_size (controlled/malicious server or reconnect), and concurrently umount/teardown so TCON_LINK_IN_TREE is already cleared when cifsFileInfo_put() drops the last tlink ref.\nPR:L - Any unprivileged user with write access on an existing CIFS mount can invoke truncate(2); vfs_truncate only requires MAY_WRITE and setattr_prepare does not demand CAP_SYS_ADMIN. CIFS is not FS_USERNS_MOUNT, but the vulnerable path itself needs no init-namespace capability.\nUI:N - The attacker performs open/truncate (and optional umount) themselves on a reachable CIFS mount such as an enterprise automount or a share they mounted; no separate victim action is required at exploit time.\nS:U - This is a standard in-kernel heap use-after-free of struct cifs_tcon on the client host, enabling privilege escalation within the same kernel security authority and not a VM, IOMMU, or sandbox escape.\nC:H - After cifsFileInfo_put() can free tcon, set_path_size()/smb2_compound_op() reads the freed cifs_tcon; kernel UAF of this heap object enables reuse/spraying and arbitrary kernel memory disclosure.\nI:H - The same freed tcon is passed into SMB2 compound operations that write tcon fields and follow tcon->ses pointers, so heap spraying yields arbitrary write and potential control-flow hijack primitives.\nA:H - Use-after-free of tcon in the path-based set_path_size fallback causes kernel oops/panic even without full exploitation, fully denying availability."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/smb/client/inode.c"], "versions": [{"version": "110fee6b9bb58a5c50047fc2594d415f741b591e", "lessThan": "4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4", "status": "affected", "versionType": "git"}, {"version": "110fee6b9bb58a5c50047fc2594d415f741b591e", "lessThan": "4bea15d9c7683218f57b8c1f5f0aa75cab76af8d", "status": "affected", "versionType": "git"}, {"version": "110fee6b9bb58a5c50047fc2594d415f741b591e", "lessThan": "b96db32fed8dfb2478d7c208f89bf383beed1535", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/smb/client/inode.c"], "versions": [{"version": "6.18", "status": "affected"}, {"version": "0", "lessThan": "6.18", "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": "6.18", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4"}, {"url": "https://git.kernel.org/stable/c/4bea15d9c7683218f57b8c1f5f0aa75cab76af8d"}, {"url": "https://git.kernel.org/stable/c/b96db32fed8dfb2478d7c208f89bf383beed1535"}], "title": "cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/smb/client/inode.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4", "status": "affected", "version": "110fee6b9bb58a5c50047fc2594d415f741b591e", "versionType": "git"}, {"lessThan": "4bea15d9c7683218f57b8c1f5f0aa75cab76af8d", "status": "affected", "version": "110fee6b9bb58a5c50047fc2594d415f741b591e", "versionType": "git"}, {"lessThan": "b96db32fed8dfb2478d7c208f89bf383beed1535", "status": "affected", "version": "110fee6b9bb58a5c50047fc2594d415f741b591e", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/smb/client/inode.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.18"}, {"lessThan": "6.18", "status": "unaffected", "version": "0", "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\ncifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size()\n\nWhen the else branch of cifs_file_set_size() finds a writable file handle\nvia find_writable_file(), it borrows tcon and server from the handle's\ntlink, attempts the handle-based set_file_size() RPC, and then releases\nthe handle with cifsFileInfo_put().\n\nIf set_file_size() fails, execution falls through to the path-based\nfallback, which reuses the borrowed tcon and server under the\n\"if (tcon == NULL)\" guard. Since tcon is not NULL at that point, the\nguard is skipped. If cifsFileInfo_put() dropped the last reference on a\ntlink that was already removed from the tlink tree (TCON_LINK_IN_TREE\ncleared, as happens during reconnection or session teardown),\ncifs_put_tlink() will have freed tcon; the subsequent set_path_size()\ncall is then a use-after-free.\n\nSetting tcon = NULL after cifsFileInfo_put() causes the existing guard\nto take the cifs_sb_tlink() path, which acquires a fresh reference for\nthe path-based operation or fails cleanly if the session is gone."}], "id": "CVE-2026-89641", "lastModified": "2026-10-19T09:18:01.287", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-11T20:19:49.867", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4bea15d9c7683218f57b8c1f5f0aa75cab76af8d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b96db32fed8dfb2478d7c208f89bf383beed1535"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel (CIFS): Use-after-free vulnerability in cifs_file_set_size()", "id": "2532505", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532505"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.7", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-825", "details": ["A flaw was found in the Linux kernel's Common Internet File System (CIFS) module. This vulnerability, a use-after-free, occurs in the `cifs_file_set_size()` function. When a file's size is being modified, a critical system resource (tcon object) can be released too early but then accessed again. A local attacker could exploit this to cause a system crash, leading to a Denial of Service (DoS), or potentially execute unauthorized code."], "name": "CVE-2026-89641", "public_date": "2026-09-11T19:45:34Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89641\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89641\nhttps://git.kernel.org/stable/c/4bea15d9c7683218f57b8c1f5f0aa75cab76af8d\nhttps://git.kernel.org/stable/c/4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4\nhttps://git.kernel.org/stable/c/b96db32fed8dfb2478d7c208f89bf383beed1535"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[110fee6b9bb58a5c50047fc2594d415f741b591e,4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[110fee6b9bb58a5c50047fc2594d415f741b591e,4bea15d9c7683218f57b8c1f5f0aa75cab76af8d)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[110fee6b9bb58a5c50047fc2594d415f741b591e,b96db32fed8dfb2478d7c208f89bf383beed1535)"}}], "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": "6.18"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.18)"}}, {"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": "2026-09-12T10:30:13.417700+00:00", "updated": "2026-09-15T21:15:14.617091+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}