CVE-2025-39964 (GCVE-0-2025-39964)
Vulnerability from cvelistv5
Published
2025-10-13 13:48
Modified
2026-10-15 01:08
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg Issuing two writes to the same af_alg socket is bogus as the data will be interleaved in an unpredictable fashion. Furthermore, concurrent writes may create inconsistencies in the internal socket state. Disallow this by adding a new ctx->write field that indiciates exclusive ownership for writing.
References
Impacted products
Vendor Product Version
Linux Linux Version: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2
Version: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2
Version: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2
Version: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2
Version: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2
Version: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2
Version: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2
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CISA Known Exploited Vulnerability
Data from the CISA Known Exploited Vulnerabilities Catalog

Date added: 2026-09-18

Due date: 2026-09-21

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.

Used in ransomware: Unknown

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

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      "containers": "{\"adp\": [{\"affected\": [{\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}], \"x_adpType\": \"supplier\", \"references\": [{\"url\": \"https://cert-portal.siemens.com/productcert/html/ssa-019113.html\"}], \"providerMetadata\": {\"orgId\": \"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\", \"shortName\": \"siemens-SADP\", \"dateUpdated\": \"2026-09-08T08:42:37.537Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-39964\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"active\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-09-18T14:40:05.718549Z\"}}}, {\"other\": {\"type\": \"kev\", \"content\": {\"dateAdded\": \"2026-09-18\", \"reference\": \"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39964\"}}}], \"references\": [{\"url\": \"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39964\", \"tags\": [\"government-resource\"]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-362\", \"description\": \"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027)\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-06-11T17:35:29.681Z\"}, \"timeline\": [{\"lang\": \"en\", \"time\": \"2026-09-18T00:00:00.000Z\", \"value\": \"CVE-2025-39964 added to CISA KEV\"}]}], \"cna\": {\"title\": \"crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg\", \"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 \\u2014 two of its own threads on a socket it owns \\u2014 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\u0027s control.\\nPR:L - `alg_create()`, `alg_bind()` and `alg_setkey()` perform no capability checks whatsoever, so any unprivileged local user \\u2014 including one inside a container or unprivileged user namespace \\u2014 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 \\u2014 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-\u003eoffset + sg-\u003elength, 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\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"8ff590903d5fc7f5a0a988c38267a3d08e6393a2\", \"lessThan\": \"0f28c4adbc4a97437874c9b669fd7958a8c6d6ce\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"8ff590903d5fc7f5a0a988c38267a3d08e6393a2\", \"lessThan\": \"e4c1ec11132ec466f7362a95f36a506ce4dc08c9\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"8ff590903d5fc7f5a0a988c38267a3d08e6393a2\", \"lessThan\": \"1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"8ff590903d5fc7f5a0a988c38267a3d08e6393a2\", \"lessThan\": \"7c4491b5644e3a3708f3dbd7591be0a570135b84\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"8ff590903d5fc7f5a0a988c38267a3d08e6393a2\", \"lessThan\": \"9aee87da5572b3a14075f501752e209801160d3d\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"8ff590903d5fc7f5a0a988c38267a3d08e6393a2\", \"lessThan\": \"45bcf60fe49b37daab1acee57b27211ad1574042\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"8ff590903d5fc7f5a0a988c38267a3d08e6393a2\", \"lessThan\": \"1b34cbbf4f011a121ef7b2d7d6e6920a036d5285\", \"versionType\": \"git\"}], \"programFiles\": [\"crypto/af_alg.c\", \"include/crypto/if_alg.h\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.6.38\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"2.6.38\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.10.245\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.194\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.154\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.108\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.49\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.16.9\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.16.*\"}, {\"status\": \"unaffected\", \"version\": \"6.17\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"crypto/af_alg.c\", \"include/crypto/if_alg.h\"], \"defaultStatus\": \"affected\"}], \"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\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"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-\u003ewrite field that indiciates\\nexclusive ownership for writing.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.245\", \"versionStartIncluding\": \"2.6.38\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.194\", \"versionStartIncluding\": \"2.6.38\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.154\", \"versionStartIncluding\": \"2.6.38\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.108\", \"versionStartIncluding\": \"2.6.38\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.49\", \"versionStartIncluding\": \"2.6.38\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.16.9\", \"versionStartIncluding\": \"2.6.38\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.17\", \"versionStartIncluding\": \"2.6.38\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T12:06:33.126Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-39964\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-09-19T03:56:17.769Z\", \"dateReserved\": \"2025-04-16T07:20:57.149Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2025-10-13T13:48:30.334Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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