{"id":"CVE-2026-74587","state":"PUBLISHED","title":"sctp: fix use-after-free of cached ASCONF chunk","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: fix use-after-free of cached ASCONF chunk\n\naddip_last_asconf caches the outstanding outbound ASCONF chunk. The normal\nASCONF-ACK completion path releases the chunk and clears the pointer.\n\nHowever, sctp_asconf_queue_teardown() releases the cached chunk without\nclearing addip_last_asconf. During peer restart handling,\nsctp_sf_do_dupcook_a() queues SCTP_CMD_PURGE_ASCONF_QUEUE, which invokes\nsctp_asconf_queue_teardown() while the association remains alive and leaves\nthe pointer dangling.\n\nA delayed authenticated ASCONF-ACK can then reach sctp_sf_do_asconf_ack(),\nwhich accesses the stale chunk and passes it to sctp_process_asconf_ack(),\ncausing a use-after-free and a second release.\n\nClearing the pointer exposes a race with T4 expiry. Peer restart handling\nqueues the timer stop before the purge, but SCTP_CMD_TIMER_STOP uses\ntimer_delete(), which does not wait for a callback already running on\nanother CPU. Such a callback can reach sctp_sf_t4_timer_expire() after\nthe purge and dereference NULL.\n\nClear addip_last_asconf after releasing the cached chunk, and make\nsctp_sf_t4_timer_expire() consume a stale T4 expiry if no outstanding\nASCONF remains.","publishedAt":"2026-08-22T15:31:39.810Z","updatedAt":"2026-10-16T19:05:58.841Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/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":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"10459b03e2d9ee12435e96f587de4d4cacdbf435","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"e1bb114e09372fd6e03387ced9ef566da336ed6c","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"179676f0166230c80053a392303485b37c93dd33","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"dc67d528c2fa939cec7fe3bf7f3089c8d281ca3d","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"618b5c6d049896fcfabb91afc072954c92cb2693","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"07daf4f9750104960a1d60831b2353c0d41f35fb","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"d949992bc3f00027a2c755e860a11950c75f6073","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"8c283e7b56adce00193837f3311b06662466fb21","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/associola.c","net/sctp/sm_statefuns.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.0","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/associola.c","net/sctp/sm_statefuns.c"]}],"references":["https://git.kernel.org/stable/c/10459b03e2d9ee12435e96f587de4d4cacdbf435","https://git.kernel.org/stable/c/e1bb114e09372fd6e03387ced9ef566da336ed6c","https://git.kernel.org/stable/c/179676f0166230c80053a392303485b37c93dd33","https://git.kernel.org/stable/c/dc67d528c2fa939cec7fe3bf7f3089c8d281ca3d","https://git.kernel.org/stable/c/618b5c6d049896fcfabb91afc072954c92cb2693","https://git.kernel.org/stable/c/07daf4f9750104960a1d60831b2353c0d41f35fb","https://git.kernel.org/stable/c/d949992bc3f00027a2c755e860a11950c75f6073","https://git.kernel.org/stable/c/8c283e7b56adce00193837f3311b06662466fb21"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74587.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74587","state":"PUBLISHED","datePublished":"2026-08-22T15:31:39.810Z","dateUpdated":"2026-10-16T19:05:58.841Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.918Z"},"containers":{"cna":{"title":"sctp: fix use-after-free of cached ASCONF chunk","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: fix use-after-free of cached ASCONF chunk\n\naddip_last_asconf caches the outstanding outbound ASCONF chunk. The normal\nASCONF-ACK completion path releases the chunk and clears the pointer.\n\nHowever, sctp_asconf_queue_teardown() releases the cached chunk without\nclearing addip_last_asconf. During peer restart handling,\nsctp_sf_do_dupcook_a() queues SCTP_CMD_PURGE_ASCONF_QUEUE, which invokes\nsctp_asconf_queue_teardown() while the association remains alive and leaves\nthe pointer dangling.\n\nA delayed authenticated ASCONF-ACK can then reach sctp_sf_do_asconf_ack(),\nwhich accesses the stale chunk and passes it to sctp_process_asconf_ack(),\ncausing a use-after-free and a second release.\n\nClearing the pointer exposes a race with T4 expiry. Peer restart handling\nqueues the timer stop before the purge, but SCTP_CMD_TIMER_STOP uses\ntimer_delete(), which does not wait for a callback already running on\nanother CPU. Such a callback can reach sctp_sf_t4_timer_expire() after\nthe purge and dereference NULL.\n\nClear addip_last_asconf after releasing the cached chunk, and make\nsctp_sf_t4_timer_expire() consume a stale T4 expiry if no outstanding\nASCONF remains."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"10459b03e2d9ee12435e96f587de4d4cacdbf435","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"e1bb114e09372fd6e03387ced9ef566da336ed6c","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"179676f0166230c80053a392303485b37c93dd33","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"dc67d528c2fa939cec7fe3bf7f3089c8d281ca3d","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"618b5c6d049896fcfabb91afc072954c92cb2693","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"07daf4f9750104960a1d60831b2353c0d41f35fb","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"d949992bc3f00027a2c755e860a11950c75f6073","versionType":"git"},{"version":"a000c01e60e40e15304ffe48fff051d17a7bea91","status":"affected","lessThan":"8c283e7b56adce00193837f3311b06662466fb21","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/associola.c","net/sctp/sm_statefuns.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.0","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/associola.c","net/sctp/sm_statefuns.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/10459b03e2d9ee12435e96f587de4d4cacdbf435"},{"url":"https://git.kernel.org/stable/c/e1bb114e09372fd6e03387ced9ef566da336ed6c"},{"url":"https://git.kernel.org/stable/c/179676f0166230c80053a392303485b37c93dd33"},{"url":"https://git.kernel.org/stable/c/dc67d528c2fa939cec7fe3bf7f3089c8d281ca3d"},{"url":"https://git.kernel.org/stable/c/618b5c6d049896fcfabb91afc072954c92cb2693"},{"url":"https://git.kernel.org/stable/c/07daf4f9750104960a1d60831b2353c0d41f35fb"},{"url":"https://git.kernel.org/stable/c/d949992bc3f00027a2c755e860a11950c75f6073"},{"url":"https://git.kernel.org/stable/c/8c283e7b56adce00193837f3311b06662466fb21"}],"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 - The UAF is triggered when the kernel processes inbound SCTP COOKIE-ECHO (peer restart) and ASCONF-ACK chunks from a remote association peer via sctp_rcv()/sctp_inq_push()/sctp_do_sm(), with no local syscall required on the victim.\nAC:L - The remote SCTP peer controls the full protocol sequence—establishing an ADDIP-capable association, waiting for the victim's outstanding ASCONF, sending COOKIE-ECHO restart to purge queues, then delivering a delayed authenticated ASCONF-ACK—without attacker-uncontrollable races or memory layout.\nPR:N - Exploitation requires only network access as an established SCTP association peer sending authenticated protocol traffic; no local Linux account, capability, or namespace privilege is needed on the victim host.\nUI:N - No victim user action is required beyond normal automated SCTP server/client operation; the attacker drives the entire trigger sequence with crafted COOKIE-ECHO and ASCONF-ACK packets on the existing association.\nS:U - Impact is confined to kernel memory corruption and potential privilege escalation within the host kernel; it does not cross a VM, container, or IOMMU security boundary.\nC:H - sctp_sf_do_asconf_ack() and sctp_process_asconf_ack() dereference the stale addip_last_asconf pointer to read freed sctp_chunk and skb metadata; UAF on slab-allocated chunk objects enables heap grooming for arbitrary kernel memory disclosure.\nI:H - The stale pointer causes sctp_process_asconf_ack() to perform a second sctp_chunk_free() on an already-freed chunk, yielding a kmem_cache double-free that can be leveraged for arbitrary kernel write or control-flow hijack.\nA:H - Dereferencing the freed cached ASCONF chunk during ASCONF-ACK processing can cause kernel oops/panic and repeatable remote denial of service against any SCTP endpoint handling the malicious peer traffic."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-25T05:40:13.798Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"5.10.265"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"5.15.216"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"6.6.152"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"6.12.104"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"6.18.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74587","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T19:01:25.161847Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:05:58.841Z"}}]}}}