{"schema_version":"1","data":[{"id":41,"advisory_id":"ceae742e-b84b-40e8-afd5-0baec053ba91","revision":1,"source_id":"core-kev","source_url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2025-39964","source_published_at":"2026-09-18T00:00:00+00:00","published_at":"2026-10-24T20:39:46.770168+00:00","extraction_method":"structured","technologies":["core-kev","kernel"],"cve_ids":["CVE-2025-39964"],"event_types":["advisory"],"payload":{"kind":"advisory","title":"Linux Kernel Race Condition Vulnerability","summary":"Linux Kernel contains a race condition vulnerability which allows concurrent writes to the same AF_ALG socket causing data to be unpredictably interleaved and creating inconsistencies in the socket's internal state. CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.","evidence":"kev:CVE-2025-39964","products":[{"name":{"value":"Kernel","evidence":"/product"},"prerequisites":[],"fixed_versions":[],"affected_versions":[]}],"severity":"unknown","structured":{"id":"CVE-2025-39964","aliases":["CVE-2025-39964"],"affected":[],"modified":"2026-09-18T00:00:00.000Z","provider":"kev","references":["https://www.cisa.gov/known-exploited-vulnerabilities-catalog"],"exploitation":{"cwes":["CWE-362"],"cveID":"CVE-2025-39964","notes":"This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce; https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9; https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8; https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84; https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d; https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042; https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2025-39964","dueDate":"2026-09-21","product":"Kernel","dateAdded":"2026-09-18","vendorProject":"Linux","requiredAction":"Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.","known_exploited":true,"shortDescription":"Linux Kernel contains a race condition vulnerability which allows concurrent writes to the same AF_ALG socket causing data to be unpredictably interleaved and creating inconsistencies in the socket's internal state.","vulnerabilityName":"Linux Kernel Race Condition Vulnerability","knownRansomwareCampaignUse":"Unknown"}},"related_cves":[{"value":"CVE-2025-39964","evidence":"/cveID"}],"security_relevant":true,"severity_evidence":null},"priority":{"reasons":["linked_severity","known_exploited"],"severity":"high","linked_cves":[{"cve":"CVE-2025-39964","metrics":[{"cvssV3_1":{"version":"3.1","baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerability is reached through the AF_ALG socket family via `socket()`/`bind()`/`sendmsg()`/`recvmsg()` syscalls, which requires local system access. There is no remote or adjacent-network path to `af_alg_sendmsg()`.\nAC:L - The attacker controls both sides of the race entirely — two of its own threads on a socket it owns — and can force writer A to park deterministically in `af_alg_wait_for_wmem()` by sizing `SO_SNDBUF` and filling it, then wake it on demand with its own `recvmsg()`. The error exit that leaves `cur == 0` is triggered at will with a deliberately faulting user buffer, so no condition is outside the attacker's control.\nPR:L - `alg_create()`, `alg_bind()` and `alg_setkey()` perform no capability checks whatsoever, so any unprivileged local user — including one inside a container or unprivileged user namespace — can open, bind and write to an AF_ALG skcipher/aead socket. The required modules are auto-loaded on demand via `MODULE_ALIAS_NETPROTO(AF_ALG)` and `request_module(\"algif-%s\")`.\nUI:N - The attacking process performs every step itself — socket creation, bind, and the two concurrent `sendmsg()` calls. No victim action or interaction of any kind is needed.\nS:U - The corruption is confined to kernel heap objects (`struct af_alg_tsgl`/scatterlist and adjacent slab memory) within the same security authority. No hypervisor, IOMMU, or other trust boundary is crossed.\nC:H - The out-of-bounds scatterlist entry is fabricated from kernel list pointers and is subsequently handed to the cipher by `skcipher_recvmsg`/`aead_recvmsg` via `af_alg_pull_tsgl()`, so arbitrary kernel memory is encrypted/decrypted and returned to userspace. This yields a kernel memory disclosure primitive, not merely a pointer leak.\nI:H - `memcpy_from_msg(page_address(sg_page(sg)) + sg->offset + sg->length, msg, len)` on the underflowed scatterlist writes attacker-controlled data of attacker-chosen length to an address derived from attacker-influenceable heap contents. Combined with heap grooming of the 4KB tsgl allocations, this is a controlled kernel write suitable for privilege escalation.\nA:H - Dereferencing `page_address(sg_page(sg))` on a bogus page_link, and the later `put_page()` on that fabricated page, reliably produce an oops/panic or page refcount corruption. Any unprivileged user can trigger this repeatedly, crashing the machine."}]}],"products":[{"name":{"value":"Linux","evidence":"/containers/cna/affected/0/product"},"prerequisites":[],"fixed_versions":[],"affected_versions":[]},{"name":{"value":"Linux","evidence":"/containers/cna/affected/1/product"},"prerequisites":[],"fixed_versions":[],"affected_versions":[]}],"severity":"high","source_id":"core-cve","source_url":"https://www.cve.org/CVERecord?id=CVE-2025-39964","relationship":"advisory","known_exploited":false,"relationship_evidence":"/cveID"}],"fix_available":false,"known_exploited":true,"publisher_severity":"unknown"},"context_update":false}],"next_after":41,"next_before":41}