{"id":"CVE-2026-63971","state":"PUBLISHED","title":"sctp: fix race between sctp_wait_for_connect and peeloff","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: fix race between sctp_wait_for_connect and peeloff\n\nsctp_wait_for_connect() drops and re-acquires the socket lock while\nwaiting for the association to reach ESTABLISHED state. During this\nwindow, another thread can peeloff the association to a new socket via\ngetsockopt(SCTP_SOCKOPT_PEELOFF), changing asoc->base.sk. After\nre-acquiring the old socket lock, sctp_wait_for_connect() returns\nsuccess without noticing the migration — the caller then accesses\nthe association under the wrong lock in sctp_datamsg_from_user().\n\nAdd the same sk != asoc->base.sk check that sctp_wait_for_sndbuf()\nalready has, returning an error if the association was migrated while\nwe slept.","publishedAt":"2026-07-19T14:55:57.792Z","updatedAt":"2026-10-19T20:17:59.440Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"0e0d5bc76fd4267a71334fcc8f1a5fbcf997845d","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"bcfeac79af740735ace44008b4a11b8e5add20f5","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"8e9b56051d24540cfbf39194618708c4a7633549","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"634a9af8a26a84d8b0d7b3b643204b344b42d9fb","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"7d2038d4b80166f7bead8d07eba3b97405816c21","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"68667ee4c7dadf7f63167234e2a1af09b3f7874e","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"6140cfa721451fa6e18e134e709703c2bf34d0fb","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"f14fe6395a8b3d961a61e138ad7b36ba3626dd4e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/socket.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/socket.c"]}],"references":["https://git.kernel.org/stable/c/0e0d5bc76fd4267a71334fcc8f1a5fbcf997845d","https://git.kernel.org/stable/c/bcfeac79af740735ace44008b4a11b8e5add20f5","https://git.kernel.org/stable/c/8e9b56051d24540cfbf39194618708c4a7633549","https://git.kernel.org/stable/c/634a9af8a26a84d8b0d7b3b643204b344b42d9fb","https://git.kernel.org/stable/c/7d2038d4b80166f7bead8d07eba3b97405816c21","https://git.kernel.org/stable/c/68667ee4c7dadf7f63167234e2a1af09b3f7874e","https://git.kernel.org/stable/c/6140cfa721451fa6e18e134e709703c2bf34d0fb","https://git.kernel.org/stable/c/f14fe6395a8b3d961a61e138ad7b36ba3626dd4e"],"weaknesses":["CWE-362"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63971.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63971","state":"PUBLISHED","datePublished":"2026-07-19T14:55:57.792Z","dateUpdated":"2026-10-19T20:17:59.440Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.024Z"},"containers":{"cna":{"title":"sctp: fix race between sctp_wait_for_connect and peeloff","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: fix race between sctp_wait_for_connect and peeloff\n\nsctp_wait_for_connect() drops and re-acquires the socket lock while\nwaiting for the association to reach ESTABLISHED state. During this\nwindow, another thread can peeloff the association to a new socket via\ngetsockopt(SCTP_SOCKOPT_PEELOFF), changing asoc->base.sk. After\nre-acquiring the old socket lock, sctp_wait_for_connect() returns\nsuccess without noticing the migration — the caller then accesses\nthe association under the wrong lock in sctp_datamsg_from_user().\n\nAdd the same sk != asoc->base.sk check that sctp_wait_for_sndbuf()\nalready has, returning an error if the association was migrated while\nwe slept."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"0e0d5bc76fd4267a71334fcc8f1a5fbcf997845d","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"bcfeac79af740735ace44008b4a11b8e5add20f5","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"8e9b56051d24540cfbf39194618708c4a7633549","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"634a9af8a26a84d8b0d7b3b643204b344b42d9fb","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"7d2038d4b80166f7bead8d07eba3b97405816c21","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"68667ee4c7dadf7f63167234e2a1af09b3f7874e","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"6140cfa721451fa6e18e134e709703c2bf34d0fb","versionType":"git"},{"version":"668c9beb9020d5834ee9e43c208190a07d2b1928","status":"affected","lessThan":"f14fe6395a8b3d961a61e138ad7b36ba3626dd4e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/socket.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/socket.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/0e0d5bc76fd4267a71334fcc8f1a5fbcf997845d"},{"url":"https://git.kernel.org/stable/c/bcfeac79af740735ace44008b4a11b8e5add20f5"},{"url":"https://git.kernel.org/stable/c/8e9b56051d24540cfbf39194618708c4a7633549"},{"url":"https://git.kernel.org/stable/c/634a9af8a26a84d8b0d7b3b643204b344b42d9fb"},{"url":"https://git.kernel.org/stable/c/7d2038d4b80166f7bead8d07eba3b97405816c21"},{"url":"https://git.kernel.org/stable/c/68667ee4c7dadf7f63167234e2a1af09b3f7874e"},{"url":"https://git.kernel.org/stable/c/6140cfa721451fa6e18e134e709703c2bf34d0fb"},{"url":"https://git.kernel.org/stable/c/f14fe6395a8b3d961a61e138ad7b36ba3626dd4e"}],"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 - Exploitation requires local syscalls on an SCTP socket (`sendmsg`/`sendto` to trigger `sctp_wait_for_connect`, and `getsockopt(SCTP_SOCKOPT_PEELOFF)` to peel off the association). A remote peer can only help complete the SCTP handshake; it cannot invoke peeloff or the racing send path.\nAC:L - The attacker controls both sides of the race by running concurrent threads on the same SCTP one-to-many socket, timing peeloff during the window where `sctp_wait_for_connect()` has released the socket lock. Required options (`SCTP_FRAGMENT_INTERLEAVE`, `SCTP_INTERLEAVING_SUPPORTED`, and `net.sctp.intl_enable`) are attacker-settable in a user/net namespace.\nPR:L - No real-root capability is required; an unprivileged user can create SCTP sockets and drive the full race from a user namespace (`unshare -Urn`), including enabling `net.sctp.intl_enable` and the interleaving socket options needed to reach the vulnerable `sctp_sendmsg_to_asoc()` path.\nUI:N - Exploitation is fully attacker-driven through coordinated local threads and does not require any action from a victim user or administrator beyond normal SCTP socket use.\nS:U - Impact is confined to kernel memory integrity/availability within the same security authority; successful exploitation would be local privilege escalation, not a cross-boundary escape such as VM or container breakout by itself.\nC:H - After peeloff migrates `asoc->base.sk`, the caller continues in `sctp_datamsg_from_user()` while holding the wrong socket lock, creating unsynchronized concurrent access to association/stream state that can corrupt kernel heap metadata and be leveraged for arbitrary kernel memory disclosure.\nI:H - The post-race path builds and queues DATA/I-DATA chunks via `sctp_datamsg_from_user()` and `sctp_primitive_SEND()` without the correct socket lock, enabling concurrent modification of association output queues and stream structures that can be turned into arbitrary kernel writes or control-flow hijacking.\nA:H - Concurrent unsynchronized access to a live SCTP association after peeloff can cause kernel oops/panic or wedged associations, and the underlying race is a classic kernel concurrency defect with high availability impact even before full exploitation."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:37:42.789Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.10.259"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.15.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.6.143"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.12.93"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.18.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.0.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-63971","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:34:18.318567Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","type":"CWE","description":"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:17:59.440Z"}}]}}}