{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39964", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.149Z", "datePublished": "2025-10-13T13:48:30.334Z", "dateUpdated": "2026-08-05T12:06:33.126Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:06:33.126Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: af_alg - Disallow concurrent writes in af_alg_sendmsg\n\nIssuing two writes to the same af_alg socket is bogus as the\ndata will be interleaved in an unpredictable fashion. Furthermore,\nconcurrent writes may create inconsistencies in the internal\nsocket state.\n\nDisallow this by adding a new ctx->write field that indiciates\nexclusive ownership for writing." } ], "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 - 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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "crypto/af_alg.c", "include/crypto/if_alg.h" ], "versions": [ { "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2", "lessThan": "0f28c4adbc4a97437874c9b669fd7958a8c6d6ce", "status": "affected", "versionType": "git" }, { "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2", "lessThan": "e4c1ec11132ec466f7362a95f36a506ce4dc08c9", "status": "affected", "versionType": "git" }, { "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2", "lessThan": "1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8", "status": "affected", "versionType": "git" }, { "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2", "lessThan": "7c4491b5644e3a3708f3dbd7591be0a570135b84", "status": "affected", "versionType": "git" }, { "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2", "lessThan": "9aee87da5572b3a14075f501752e209801160d3d", "status": "affected", "versionType": "git" }, { "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2", "lessThan": "45bcf60fe49b37daab1acee57b27211ad1574042", "status": "affected", "versionType": "git" }, { "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2", "lessThan": "1b34cbbf4f011a121ef7b2d7d6e6920a036d5285", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "crypto/af_alg.c", "include/crypto/if_alg.h" ], "versions": [ { "version": "2.6.38", "status": "affected" }, { "version": "0", "lessThan": "2.6.38", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.245", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.194", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.154", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.108", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.49", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.9", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "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": "2.6.38", "versionEndExcluding": "5.10.245" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.38", "versionEndExcluding": "5.15.194" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.38", "versionEndExcluding": "6.1.154" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.38", "versionEndExcluding": "6.6.108" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.38", "versionEndExcluding": "6.12.49" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.38", "versionEndExcluding": "6.16.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.38", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce" }, { "url": "https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9" }, { "url": "https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8" }, { "url": "https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84" }, { "url": "https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d" }, { "url": "https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042" }, { "url": "https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285" } ], "title": "crypto: af_alg - 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