CVE-2026-63867

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63867", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.017Z", "datePublished": "2026-07-19T14:18:37.234Z", "dateUpdated": "2026-10-19T20:17:53.288Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:36:43.517Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: close TOCTOU race while computing rcv_wnd\n\nThe MPTCP output path access locklessly the MPTCP-level ack_seq\nin multiple times, using possibly different values for the data_ack\nin the DSS option and to compute the announced rcv wnd for the same\npacket.\n\nRefactor the cote to avoid inconsistencies which may confuse the\npeer. Also ensure that the MPTCP level rcv wnd is updated only when\nthe egress packet actually contains a DSS ack."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H", "baseScore": 8.2, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:N - The flaw is in the MPTCP TCP output path (`__tcp_transmit_skb()` \u2192 `mptcp_established_options_dss()` / `mptcp_write_options()`), reachable by any remote peer that can exchange MPTCP packets over the network.\nAC:L - The attacker controls both sides of the race by timing concurrent ingress traffic (advancing `msk->ack_seq` on receive) against egress transmissions on the same or another subflow; no special memory layout or victim-specific state is required.\nPR:N - Exploitation requires only the ability to complete an MPTCP/TCP connection as a remote peer; no local privileges, capabilities, or authenticated access to the victim system is needed.\nUI:N - Exploitation is fully automated over the network once an MPTCP connection is established; no victim user action is required beyond normal service connectivity.\nS:U - The impact is confined to the kernel networking stack and the affected MPTCP connection state; it does not cross a VM, sandbox, or IOMMU security boundary.\nC:N - This is a protocol-state TOCTOU inconsistency, not a memory-safety bug; it does not provide arbitrary or bounded kernel memory disclosure.\nI:L - Inconsistent DSS ACK versus receive-window tracking can corrupt MPTCP-level window state (`rcv_wnd_sent`), allowing acceptance or handling of data outside the window actually announced to the peer.\nA:H - A remote attacker can repeatedly trigger the race to cause connection disruption (reset/fallback), stall MPTCP sessions, and inflate out-of-order receive buffering via incorrect `rcv_wnd_sent` values, denying service to applications using the connection."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/mptcp/options.c"], "versions": [{"version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "301a33fd590c408a05c5df800e0cc1e6a8a2f8f8", "status": "affected", "versionType": "git"}, {"version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "68364963e5baf03f16b4420292291f75c8f66497", "status": "affected", "versionType": "git"}, {"version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "907ac6b1658e0277f979fcdfae2a753b495c1510", "status": "affected", "versionType": "git"}, {"version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "c4f4cf60797974873dbc8e100144682a6f2f861f", "status": "affected", "versionType": "git"}, {"version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "3b8cbba7c0ed31189c89f90be247b8973ffa79ef", "status": "affected", "versionType": "git"}, {"version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "8f4f0a157e8436a05bf8c3670b24dbc258911c43", "status": "affected", "versionType": "git"}, {"version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "8ab24fdebc369c0dfb90f82c1650b1e66662bb45", "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/mptcp/options.c"], "versions": [{"version": "5.11", "status": "affected"}, {"version": "0", "lessThan": "5.11", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.94", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.36", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0.13", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1", "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": "5.11", "versionEndExcluding": "5.15.210"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.1.176"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.6.143"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.12.94"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.18.36"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "7.0.13"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "7.1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8"}, {"url": "https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497"}, {"url": "https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510"}, {"url": "https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f"}, {"url": "https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef"}, {"url": "https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43"}, {"url": "https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45"}], "title": "mptcp: close TOCTOU race while computing rcv_wnd", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-63867", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-16T15:32:35.077407Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-362", "description": "CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"}]}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-19T20:17:53.288Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-63867", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-16T15:32:35.077407Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T15:32:35.657Z"}}], "cna": {"title": "mptcp: close TOCTOU race while computing rcv_wnd", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 8.2, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H"}, "scenarios": [{"lang": "en", "value": "AV:N - The flaw is in the MPTCP TCP output path (`__tcp_transmit_skb()` \u2192 `mptcp_established_options_dss()` / `mptcp_write_options()`), reachable by any remote peer that can exchange MPTCP packets over the network.\nAC:L - The attacker controls both sides of the race by timing concurrent ingress traffic (advancing `msk->ack_seq` on receive) against egress transmissions on the same or another subflow; no special memory layout or victim-specific state is required.\nPR:N - Exploitation requires only the ability to complete an MPTCP/TCP connection as a remote peer; no local privileges, capabilities, or authenticated access to the victim system is needed.\nUI:N - Exploitation is fully automated over the network once an MPTCP connection is established; no victim user action is required beyond normal service connectivity.\nS:U - The impact is confined to the kernel networking stack and the affected MPTCP connection state; it does not cross a VM, sandbox, or IOMMU security boundary.\nC:N - This is a protocol-state TOCTOU inconsistency, not a memory-safety bug; it does not provide arbitrary or bounded kernel memory disclosure.\nI:L - Inconsistent DSS ACK versus receive-window tracking can corrupt MPTCP-level window state (`rcv_wnd_sent`), allowing acceptance or handling of data outside the window actually announced to the peer.\nA:H - A remote attacker can repeatedly trigger the race to cause connection disruption (reset/fallback), stall MPTCP sessions, and inflate out-of-order receive buffering via incorrect `rcv_wnd_sent` values, denying service to applications using the connection."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "301a33fd590c408a05c5df800e0cc1e6a8a2f8f8", "versionType": "git"}, {"status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "68364963e5baf03f16b4420292291f75c8f66497", "versionType": "git"}, {"status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "907ac6b1658e0277f979fcdfae2a753b495c1510", "versionType": "git"}, {"status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "c4f4cf60797974873dbc8e100144682a6f2f861f", "versionType": "git"}, {"status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "3b8cbba7c0ed31189c89f90be247b8973ffa79ef", "versionType": "git"}, {"status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "8f4f0a157e8436a05bf8c3670b24dbc258911c43", "versionType": "git"}, {"status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "lessThan": "8ab24fdebc369c0dfb90f82c1650b1e66662bb45", "versionType": "git"}], "programFiles": ["net/mptcp/options.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "5.11"}, {"status": "unaffected", "version": "0", "lessThan": "5.11", "versionType": "semver"}, {"status": "unaffected", "version": "5.15.210", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.176", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.143", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.94", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.36", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.0.13", "versionType": "semver", "lessThanOrEqual": "7.0.*"}, {"status": "unaffected", "version": "7.1", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/mptcp/options.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8"}, {"url": "https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497"}, {"url": "https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510"}, {"url": "https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f"}, {"url": "https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef"}, {"url": "https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43"}, {"url": "https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: close TOCTOU race while computing rcv_wnd\n\nThe MPTCP output path access locklessly the MPTCP-level ack_seq\nin multiple times, using possibly different values for the data_ack\nin the DSS option and to compute the announced rcv wnd for the same\npacket.\n\nRefactor the cote to avoid inconsistencies which may confuse the\npeer. Also ensure that the MPTCP level rcv wnd is updated only when\nthe egress packet actually contains a DSS ack."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.210", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.176", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.143", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.94", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.36", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.0.13", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.1", "versionStartIncluding": "5.11"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:36:43.517Z"}}}, "cveMetadata": {"cveId": "CVE-2026-63867", "state": "PUBLISHED", "dateUpdated": "2026-10-19T20:17:53.288Z", "dateReserved": "2026-07-19T07:54:57.017Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-07-19T14:18:37.234Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/mptcp/options.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "301a33fd590c408a05c5df800e0cc1e6a8a2f8f8", "status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "versionType": "git"}, {"lessThan": "68364963e5baf03f16b4420292291f75c8f66497", "status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "versionType": "git"}, {"lessThan": "907ac6b1658e0277f979fcdfae2a753b495c1510", "status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "versionType": "git"}, {"lessThan": "c4f4cf60797974873dbc8e100144682a6f2f861f", "status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "versionType": "git"}, {"lessThan": "3b8cbba7c0ed31189c89f90be247b8973ffa79ef", "status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "versionType": "git"}, {"lessThan": "8f4f0a157e8436a05bf8c3670b24dbc258911c43", "status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "versionType": "git"}, {"lessThan": "8ab24fdebc369c0dfb90f82c1650b1e66662bb45", "status": "affected", "version": "fa3fe2b150316b294f2c662653501273ff25bba8", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/mptcp/options.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.11"}, {"lessThan": "5.11", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.210", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.176", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.143", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.94", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.36", "versionType": "semver"}, {"lessThanOrEqual": "7.0.*", "status": "unaffected", "version": "7.0.13", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.1", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "5E938CDF-D1C4-43D0-98DC-9E11B6B55801", "versionEndExcluding": "5.15.210", "versionStartIncluding": "5.11", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "C4446623-5F2B-4DD8-8666-9FAAC285A757", "versionEndExcluding": "6.1.176", "versionStartIncluding": "5.16", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "9062F1CD-CAD6-4EA2-A73F-C06D4A887B8C", "versionEndExcluding": "6.6.143", "versionStartIncluding": "6.2", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "85421C0C-ABDE-4357-971C-67F9087DE1B9", "versionEndExcluding": "6.12.94", "versionStartIncluding": "6.7", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "389025D2-958D-41BD-BD96-70ED1033A9F3", "versionEndExcluding": "6.18.36", "versionStartIncluding": "6.13", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "6A64BF9F-3BCA-42FD-98CB-8F03474D2B1E", "versionEndExcluding": "7.0.13", "versionStartIncluding": "6.19", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*", "matchCriteriaId": "B1EF7059-E670-45F4-B422-54C40FA86390", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*", "matchCriteriaId": "0D38F0BF-A728-4133-A358-D44A2F7EE6D6", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*", "matchCriteriaId": "EC732D08-5F7B-46D9-B154-E60C7F4F0A97", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*", "matchCriteriaId": "E5910A9D-F60A-409A-B486-FE66BFEBA9B9", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:*", "matchCriteriaId": "81DFF19E-9CF8-49C6-8C36-1E4038622933", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:*", "matchCriteriaId": "B0E8FC71-3952-444C-83E9-718DBBBEC615", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: close TOCTOU race while computing rcv_wnd\n\nThe MPTCP output path access locklessly the MPTCP-level ack_seq\nin multiple times, using possibly different values for the data_ack\nin the DSS option and to compute the announced rcv wnd for the same\npacket.\n\nRefactor the cote to avoid inconsistencies which may confuse the\npeer. Also ensure that the MPTCP level rcv wnd is updated only when\nthe egress packet actually contains a DSS ack."}], "id": "CVE-2026-63867", "lastModified": "2026-10-26T16:49:22.910", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 4.2, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-63867", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T15:32:35.077407Z", "version": "2.0.3"}}]}, "published": "2026-07-19T15:16:53.617", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-367"}], "source": "nvd@nist.gov", "type": "Primary"}, {"description": [{"lang": "en", "value": "CWE-362"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "kernel: mptcp: close TOCTOU race while computing rcv_wnd", "id": "2502304", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2502304"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-367", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nmptcp: close TOCTOU race while computing rcv_wnd\nThe MPTCP output path access locklessly the MPTCP-level ack_seq\nin multiple times, using possibly different values for the data_ack\nin the DSS option and to compute the announced rcv wnd for the same\npacket.\nRefactor the cote to avoid inconsistencies which may confuse the\npeer. Also ensure that the MPTCP level rcv wnd is updated only when\nthe egress packet actually contains a DSS ack.", "A flaw was found in the Linux kernel's Multipath TCP (MPTCP) implementation. A race condition exists when computing the receive window, where the acknowledgment sequence number is accessed without proper locking. This can lead to inconsistencies in how the receive window is calculated and communicated to a peer, potentially causing connection instability or disruption."], "name": "CVE-2026-63867", "package_state": [{"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "impact": "important", "package_name": "erlang27", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-07-19T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-63867\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-63867\nhttps://lore.kernel.org/linux-cve-announce/2026071912-CVE-2026-63867-eac1@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[fa3fe2b150316b294f2c662653501273ff25bba8,301a33fd590c408a05c5df800e0cc1e6a8a2f8f8)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[fa3fe2b150316b294f2c662653501273ff25bba8,68364963e5baf03f16b4420292291f75c8f66497)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[fa3fe2b150316b294f2c662653501273ff25bba8,907ac6b1658e0277f979fcdfae2a753b495c1510)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[fa3fe2b150316b294f2c662653501273ff25bba8,c4f4cf60797974873dbc8e100144682a6f2f861f)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[fa3fe2b150316b294f2c662653501273ff25bba8,3b8cbba7c0ed31189c89f90be247b8973ffa79ef)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[fa3fe2b150316b294f2c662653501273ff25bba8,8f4f0a157e8436a05bf8c3670b24dbc258911c43)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[fa3fe2b150316b294f2c662653501273ff25bba8,8ab24fdebc369c0dfb90f82c1650b1e66662bb45)"}}], "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": "semver", "value": "5.11"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,5.11)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.15.210,5.16.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.176,6.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.143,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.94,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.36,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.0.13,7.1.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.1,*]"}}], "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": "2026-07-21T06:00:01.942872+00:00", "updated": "2026-10-20T08:45:07.977206+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}