Vulnerability details
CVE-2025-39964
Actively exploited
Linux LinuxSiemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFPSiemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPSiemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg
CVSS 3.1
7.8High
Remedy
Required action (CISA): 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. (due: 2026-09-21)
Versions not listed as affected in the CVE record:
- Linux — version 0f28c4adbc4a97437874c9b669fd7958a8c6d6ce and later
- Linux — version e4c1ec11132ec466f7362a95f36a506ce4dc08c9 and later
- Linux — version 1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8 and later
- Linux — version 7c4491b5644e3a3708f3dbd7591be0a570135b84 and later
- Linux — version 9aee87da5572b3a14075f501752e209801160d3d and later
- Linux — version 45bcf60fe49b37daab1acee57b27211ad1574042 and later
Official description
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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 7.8High | 3.1 | CVEProject cvelistV5 (CNA) (Linux) | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| Linux | Linux | 2.6.38 | CVEProject cvelistV5 (CNA) |
| Linux | Linux | 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 ≤ v < e4c1ec11132ec466f7362a95f36a506ce4dc08c9 | CVEProject cvelistV5 (CNA) |
| Linux | Linux | 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 ≤ v < 1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8 | CVEProject cvelistV5 (CNA) |
| Linux | Linux | 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 ≤ v < 7c4491b5644e3a3708f3dbd7591be0a570135b84 | CVEProject cvelistV5 (CNA) |
| Linux | Linux | 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 ≤ v < 9aee87da5572b3a14075f501752e209801160d3d | CVEProject cvelistV5 (CNA) |
| Linux | Linux | 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 ≤ v < 45bcf60fe49b37daab1acee57b27211ad1574042 | CVEProject cvelistV5 (CNA) |
| Linux | Linux | 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 ≤ v < 1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 | CVEProject cvelistV5 (CNA) |
| Linux | Linux | 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 ≤ v < 0f28c4adbc4a97437874c9b669fd7958a8c6d6ce | CVEProject cvelistV5 (CNA) |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.7 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.7 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.7 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.7 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 ≤ v | CVEProject cvelistV5 (CNA) |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.7 ≤ v | CVEProject cvelistV5 (CNA) |
References and advisories
10- 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
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39964 government-resource
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
Kolun on Telegram @kolunsec
Exploited CVEs, key news and a daily digest
Alerts for this product's next CVEsFollow the product to get new vulnerabilities on Telegram.
Details
- Published
- 2025-10-13
- Last updated
- 2026-11-10
- State
- Published
- Assigner (CNA)
- Linux
- Kolun priority
- 81 · Critical
CISA KEV catalog
- Date added
- 2026-09-18
- Due date
- 2026-09-21
- Used in ransomware
- Unknown
Exploit prediction (EPSS)
1.6%
Probability of exploitation in 30 days
76.2%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- No
- Exploitation
- Active
- Technical impact
- Total
Weaknesses (CWE)
- CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')