CVE-2025-39964
What it is
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.
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.
- In the wild
- CISA lists this as exploited in real attacks. Treat as urgent.
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- 2026-09-18 Exploited in the wildAdded to CISA's Known Exploited Vulnerabilities list
- 2026-09-21 Remediation deadlineCISA's due date for federal agencies to fix it
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: yes, CISA lists it. This puts it above everything that is not.
- Exploit odds: 1.6% in the next 30 days (EPSS).
- Severity: 7.8 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Added to CISA KEV
- 2026-09-18
- Exploit probability
- 1.6% · EPSS, next 30 days
- Weakness
- CWE-362 · Race condition
- Record status
- Analyzed
Affected
- Linux Kernel < 5.10.245
- Linux Kernel < 5.15.194
- Linux Kernel < 6.1.154
- Linux Kernel < 6.6.108
- Linux Kernel < 6.12.49
- Linux Kernel < 6.16.9
- Linux Kernel 6.17
- Siemens Simatic s7-1500 Cpu 1518-4 pn\/dp Mfp Firmware
Attack profile CVSS 3.1 · 7.8
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2025-39964.md and follow it. Check whether this project is affected by CVE-2025-39964. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce
- https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285
- https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8
- https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042
- https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84
- https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d
- https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9
References
- https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce
- https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285
- https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8
- https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042
- https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84
- https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d
- https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39964