{"id":"CVE-2025-39964","title":"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…","summary":"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…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-362","CWE-366"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 2.6.38, < 5.10.245","linux_kernel >= 5.11, < 5.15.194","linux_kernel >= 5.16, < 6.1.154","linux_kernel >= 6.2, < 6.6.108","linux_kernel >= 6.7, < 6.12.49","linux_kernel >= 6.13, < 6.16.9","linux_kernel = 6.17","simatic_s7-1500_cpu_1518-4_pn/dp_mfp_firmware >= 3.1.6","simatic_s7-1500_cpu_1518f-4_pn/dp_mfp_firmware >= 3.1.6"],"patched":["linux_kernel 6.16.9"],"published":"2025-10-13","updated":"2026-09-19","sourceUpdated":"2026-09-19T04:17:48.307","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-39964","references":[{"url":"https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39964","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39964.json"},{"url":"https://access.redhat.com/security/cve/CVE-2025-39964"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2403545"},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-39964"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-39964"},{"url":"https://lore.kernel.org/linux-cve-announce/2025101334-CVE-2025-39964-7964@gregkh/T"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog"}],"tags":["nvd","cve.org","in-the-wild","exploit-available","kev","csaf","vex","red-hat"],"exploited":true,"exploitAvailable":true,"ssvc":{"exploitation":"active","automatable":"no","technicalImpact":"total","timestamp":"2026-09-18T14:40:05.718549Z"},"epss":0.0079,"epssPercentile":0.54297,"kev":true,"kevDateAdded":"2026-09-18","kevDueDate":"2026-09-21","kevRansomware":false,"exploits":{"github":2,"githubRepos":["https://github.com/n1k0oowang/CVE-2025-39964_EXP","https://github.com/suominen/CVE-2025-39964"],"checkedAt":"2026-09-21T15:27:24.797Z"},"ingestedAt":"2026-09-08T15:33:26.996Z","scores":{"nvd":7.8,"vendor":7.3},"slug":"CVE-2025-39964","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `linux_kernel >= 2.6.38, < 5.10.245`\n- `linux_kernel >= 5.11, < 5.15.194`\n- `linux_kernel >= 5.16, < 6.1.154`\n- `linux_kernel >= 6.2, < 6.6.108`\n- `linux_kernel >= 6.7, < 6.12.49`\n- `linux_kernel >= 6.13, < 6.16.9`\n- `linux_kernel = 6.17`\n- `simatic_s7-1500_cpu_1518-4_pn/dp_mfp_firmware >= 3.1.6`\n- `simatic_s7-1500_cpu_1518f-4_pn/dp_mfp_firmware >= 3.1.6`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.16.9`\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux for NVIDIA 26 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39964.json)","depth":"abyssal","depthScore":68,"depthScoreParts":{"impact":42.9,"likelihood":0.2,"exploitation":25,"ransomware":0},"changes":[{"seq":207449,"id":"CVE-2025-39964","ts":1789761005353,"field":"kev","old":"false","new":"true"},{"seq":206868,"id":"CVE-2025-39964","ts":1789742655977,"field":"exploited","old":"false","new":"true"}]}