7.8

CVE-2025-39964: Linux Kernel Race Condition Vulnerability

KEV
Analyzed
AliasesUBUNTU-CVE-2025-39964DEBIAN-CVE-2025-39964CGA-243h-p34v-2r53
Published 13-10-2025Last modified 15-10-2026

Vulnerability summary

CVE-2025-39964 is a high (CVSS 7.8) vulnerability in Linux Kernel. It is known to be exploited: CISA lists it, first on 18-09-2026. EPSS estimates a 1.61% chance of exploitation in the next 30 days, higher than 75.9% of scored vulnerabilities.

Priority
Act nowlisted as exploited

Listed as exploited by CISA (18-09-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.8/10
010
High · v3.1 (CVE.org)
EPSS score
1.61%
0%100%
Low · +0.61 pp in 30 days
KEVExploited in the wildCritical · listed in 1 catalog
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 82 · Related 61
DLA-4379-1DLA-4404-1DSA-6053-1MGASA-2025-0309MGASA-2025-0310OPENSUSE-SU-2026:20416-1

Timeline

  1. 13-10-2025
    PublishedVulnerability first disclosed.
  2. 18-09-2026
    Added to CISA KEVExploitedLinux Kernel Race Condition Vulnerability
  3. 21-09-2026
    CISA remediation dueDeadline passedApply mitigations per vendor instructions.
  4. 15-10-2026
    Last modifiedVulnerability information updated.

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 metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

1.61%

Chance of exploitation in the next 30 days

Percentile

76%

Versus all other CVEs

30-day change

Increase +0.61 pp

From 1.00% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
18-09-2026
Federal due date
21-09-2026
ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

CISA 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. git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9 git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8 git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84 git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042 git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 nvd.nist.gov/vuln/detail/CVE-2025-39964

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu146 products
  • linuxAll versions (No fix recorded) | < 4.4.0-276.310 | < 4.15.0-245.257 | < 5.4.0-224.244 | < 5.15.0-164.174 | < 6.8.0-90.91
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 4.4.0-1150.156 | < 4.4.0-1188.203 | < 4.15.0-1187.200 | < 5.4.0-1153.163 | < 5.15.0-1098.105 | < 6.8.0-1044.46
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Chainguard16 products
  • linux-aws-6.12< 6.12.76-r0
  • linux-aws-6.18< 6.18.17-r0
  • linux-azure-6.12< 6.12.76-r0
  • linux-azure-6.18< 6.18.17-r0
  • linux-desktop-6.18< 6.18.48-r0
Linux2 products
  • linux≥ 8ff590903d5fc7f5a0a988c38267a3d08e6393a2, < 0f28c4adbc4a97437874c9b669fd7958a8c6d6ce | ≥ 8ff590903d5fc7f5a0a988c38267a3d08e6393a2, < e4c1ec11132ec466f7362a95f36a506ce4dc08c9 | ≥ 8ff590903d5fc7f5a0a988c38267a3d08e6393a2, < 1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8 | ≥ 8ff590903d5fc7f5a0a988c38267a3d08e6393a2, < 7c4491b5644e3a3708f3dbd7591be0a570135b84 | ≥ 8ff590903d5fc7f5a0a988c38267a3d08e6393a2, < 9aee87da5572b3a14075f501752e209801160d3d | ≥ 8ff590903d5fc7f5a0a988c38267a3d08e6393a2, < 45bcf60fe49b37daab1acee57b27211ad1574042 | ≥ 8ff590903d5fc7f5a0a988c38267a3d08e6393a2, < 1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 | 2.6.38
  • linux_kernel≥ 2.6.38, < 5.10.245 | ≥ 5.11, < 5.15.194 | ≥ 5.16, < 6.1.154 | ≥ 6.2, < 6.6.108 | ≥ 6.7, < 6.12.49 | ≥ 6.13, < 6.16.9 | 6.17:rc1 | 6.17:rc2 | 6.17:rc3 | 6.17:rc4 | 6.17:rc5 | 6.17:rc6
Siemens2 products
Debian1 product
  • linux< 6.1.158-1 | < 6.12.57-1 | < 6.16.9-1

5 vendors · 167 products

References

49 links
Show all 49 references