CVE-2025-39964 (GCVE-0-2025-39964)

Vulnerability from cvelistv5 – Published: 2025-10-13 13:48 – Updated: 2026-10-15 01:08
VLAI CISA Previdian
Title
crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg
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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: active Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-18 00:00 UTC
CWE
  • CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6637 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 0f28c4adbc4a97437874c9b669fd7958a8c6d6ce (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < e4c1ec11132ec466f7362a95f36a506ce4dc08c9 (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8 (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 7c4491b5644e3a3708f3dbd7591be0a570135b84 (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 9aee87da5572b3a14075f501752e209801160d3d (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 45bcf60fe49b37daab1acee57b27211ad1574042 (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.38
Unaffected: 0 , < 2.6.38 (semver)
Unaffected: 5.10.245 , ≤ 5.10.* (semver)
Unaffected: 5.15.194 , ≤ 5.15.* (semver)
Unaffected: 6.1.154 , ≤ 6.1.* (semver)
Unaffected: 6.6.108 , ≤ 6.6.* (semver)
Unaffected: 6.12.49 , ≤ 6.12.* (semver)
Unaffected: 6.16.9 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.7 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.7 , < * (custom)
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Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.7 , < * (custom)
guessed Create a notification for this product.
CISA
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 800a8b88-7155-4660-b969-5375bef45b31

Vulnerability ID: CVE-2025-39964

Status: Confirmed

Status Updated: 2026-09-18 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2026-09-18
Asserted: 2026-09-18
Scope
Notes: Linux Kernel Race Condition Vulnerability | Affected: Linux / Kernel | Description: Linux Kernel contains a race condition vulnerability which allows concurrent writes to the same AF_ALG socket causing data to be unpredictably interleaved and creating inconsistencies in the socket's internal state. | 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. | Due date: 2026-09-21 | Known ransomware campaign use (KEV): Unknown | Notes (KEV): 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
Evidence

Type: Vendor Report

Signal: Successful Exploitation

Confidence: 80%

Source: cisa-kev

Details
Cwes CWE-362
Feed CISA Known Exploited Vulnerabilities Catalog
Product Kernel
Due Date 2026-09-21
Date Added 2026-09-18
Vendorproject Linux
Vulnerabilityname Linux Kernel Race Condition Vulnerability
Knownransomwarecampaignuse Unknown
References
Created: 2026-09-18 15:00 UTC | Updated: 2026-09-18 15:00 UTC
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: c08087db-a0b9-45b6-89d2-96c69b1906f3

Vulnerability ID: CVE-2025-39964

Status: Confirmed

Status Updated: 2026-09-18 14:30 UTC

Exploited: Yes

Timestamps
First Seen: 2026-09-18
Asserted: 2026-09-18
Scope
Notes: crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg | Affected: Linux / Linux | CVSS: 7.8 (HIGH) | EPSS: 0.00323 | Used in malware: unknown | Not yet in CISA KEV: False
Evidence

Type: Public Report

Signal: Successful Exploitation

Confidence: 70%

Source: previdian

Details
Feed Previdian (previdian.com)
Title crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg
Cve Id CVE-2025-39964
Vendor Linux
Ghsa Id GHSA-WR5G-MFHW-RPFJ
Product Linux
Added Date 2026-09-18T14:30:42.702Z
Cvss Score 7.8
Epss Score 0.00323
Previous Ids
Cvss Severity HIGH
Virtual Patch False
Cvss Estimated False
Epss Percentile 0.25599
Used In Malware unknown
Vulnerability Id CVE-2025-39964
Ahead Of Cisa Kev None
Not Yet In Cisa Kev False
References
Created: 2026-09-19 15:00 UTC | Updated: 2026-09-19 15:00 UTC
Show details on NVD website
To clipboard 

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}



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