{"id":"CVE-2026-74436","state":"PUBLISHED","title":"rxrpc: serialize kernel accept preallocation with socket teardown","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: serialize kernel accept preallocation with socket teardown\n\nrxrpc_kernel_charge_accept() reads rx->backlog without any\nsocket/backlog synchronization and passes that raw pointer into\nrxrpc_service_prealloc_one(). A concurrent rxrpc_discard_prealloc()\nsets rx->backlog = NULL and frees the backlog rings, so a kernel\npreallocation worker can keep using a freed struct rxrpc_backlog\nwhile updating *_backlog_head/tail and array slots.\n\nSerialize the state check and backlog lookup with the socket lock,\nand reject kernel preallocation once teardown has disabled\nlistening or discarded the service backlog.","publishedAt":"2026-08-15T05:59:34.687Z","updatedAt":"2026-10-16T19:05:45.032Z","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":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"d6207326b4ca0ae1041281b6af9df53f8080669a","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"11b429b84c87cb5a0152f14e7d6cb649ed363901","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"c20d983968f239574290cf804a58cde18ad1c559","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"0337cdba0c477f176c0459bed012109453184573","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"dfa0b2bbc5e50119f89c6b5407faa5ed86dfa7c5","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"35a967ff8b24db09ee429c39c5b5e6571639997d","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"1741378a7a83dfd8e53a9196730df709b903cd33","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"dc175389b18c29a5303ee83169ec653adfae3e17","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/call_accept.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.9","versionType":"semver"},{"version":"5.10.266","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.217","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.184","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","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/rxrpc/call_accept.c"]}],"references":["https://git.kernel.org/stable/c/d6207326b4ca0ae1041281b6af9df53f8080669a","https://git.kernel.org/stable/c/11b429b84c87cb5a0152f14e7d6cb649ed363901","https://git.kernel.org/stable/c/c20d983968f239574290cf804a58cde18ad1c559","https://git.kernel.org/stable/c/0337cdba0c477f176c0459bed012109453184573","https://git.kernel.org/stable/c/dfa0b2bbc5e50119f89c6b5407faa5ed86dfa7c5","https://git.kernel.org/stable/c/35a967ff8b24db09ee429c39c5b5e6571639997d","https://git.kernel.org/stable/c/1741378a7a83dfd8e53a9196730df709b903cd33","https://git.kernel.org/stable/c/dc175389b18c29a5303ee83169ec653adfae3e17"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74436.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74436","state":"PUBLISHED","datePublished":"2026-08-15T05:59:34.687Z","dateUpdated":"2026-10-16T19:05:45.032Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.896Z"},"containers":{"cna":{"title":"rxrpc: serialize kernel accept preallocation with socket teardown","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: serialize kernel accept preallocation with socket teardown\n\nrxrpc_kernel_charge_accept() reads rx->backlog without any\nsocket/backlog synchronization and passes that raw pointer into\nrxrpc_service_prealloc_one(). A concurrent rxrpc_discard_prealloc()\nsets rx->backlog = NULL and frees the backlog rings, so a kernel\npreallocation worker can keep using a freed struct rxrpc_backlog\nwhile updating *_backlog_head/tail and array slots.\n\nSerialize the state check and backlog lookup with the socket lock,\nand reject kernel preallocation once teardown has disabled\nlistening or discarded the service backlog."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"d6207326b4ca0ae1041281b6af9df53f8080669a","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"11b429b84c87cb5a0152f14e7d6cb649ed363901","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"c20d983968f239574290cf804a58cde18ad1c559","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"0337cdba0c477f176c0459bed012109453184573","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"dfa0b2bbc5e50119f89c6b5407faa5ed86dfa7c5","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"35a967ff8b24db09ee429c39c5b5e6571639997d","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"1741378a7a83dfd8e53a9196730df709b903cd33","versionType":"git"},{"version":"00e907127e6f86d0f9b122d9b4347a8aa09a8b61","status":"affected","lessThan":"dc175389b18c29a5303ee83169ec653adfae3e17","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/call_accept.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.9","versionType":"semver"},{"version":"5.10.266","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.217","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.184","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","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/rxrpc/call_accept.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/d6207326b4ca0ae1041281b6af9df53f8080669a"},{"url":"https://git.kernel.org/stable/c/11b429b84c87cb5a0152f14e7d6cb649ed363901"},{"url":"https://git.kernel.org/stable/c/c20d983968f239574290cf804a58cde18ad1c559"},{"url":"https://git.kernel.org/stable/c/0337cdba0c477f176c0459bed012109453184573"},{"url":"https://git.kernel.org/stable/c/dfa0b2bbc5e50119f89c6b5407faa5ed86dfa7c5"},{"url":"https://git.kernel.org/stable/c/35a967ff8b24db09ee429c39c5b5e6571639997d"},{"url":"https://git.kernel.org/stable/c/1741378a7a83dfd8e53a9196730df709b903cd33"},{"url":"https://git.kernel.org/stable/c/dc175389b18c29a5303ee83169ec653adfae3e17"}],"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 - RxRPC is a UDP network protocol; remote peers can send packets to AFS callback-manager listeners (port 7001) that instantiate incoming calls and queue kernel preallocation work reaching rxrpc_kernel_charge_accept().\nAC:L - The attacker controls the preallocation side by flooding concurrent rxrpc/AFS callback traffic while a peer thread tears down the same socket via listen(0), shutdown, or close during AFS netns exit, creating a winnable race.\nPR:N - No local account, capability, or authentication is required to reach the vulnerable preallocation path; any remote host that can deliver rxrpc/UDP packets to a listening AFS callback manager can drive the charge_accept worker.\nUI:N - Exploitation requires no victim interaction beyond normal background AFS service operation; the attacker triggers the bug purely through network traffic timed against automatic or administrative socket teardown.\nS:U - The use-after-free corrupts kernel heap metadata and rxrpc backlog structures within kernel memory, enabling local privilege escalation but not crossing a VM, container, or IOMMU security boundary by itself.\nC:H - Concurrent use of a freed struct rxrpc_backlog allows reads and corruption of recycled slab memory, providing a standard kmalloc UAF primitive that can leak kernel pointers and sensitive data.\nI:H - The race writes peer, connection, and call pointers plus head/tail indices into freed backlog ring slots, enabling heap grooming and arbitrary kernel memory corruption exploitable for code execution.\nA:H - Use-after-free on the backlog structure during concurrent head/tail and pointer-array updates can cause kernel oops, panic, or hang, and repeated triggering enables sustained denial of service."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-23T12:47:16.782Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.10.266"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.15.217"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.1.184"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.6.148"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.12.101"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74436","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T18:56:22.698412Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:05:45.032Z"}}]}}}