Known Exploited Vulnerability
7.8
HIGH CVSS 3.1
CVE-2025-39964
Linux Kernel Race Condition Vulnerability - [Actively Exploited]
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.

INFO

Published Date :

Oct. 13, 2025, 2:15 p.m.

Last Modified :

Sept. 19, 2026, 4:17 a.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

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.

Known Ransomware Campaign Use:

Unknown

Notes :

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

Affected Products

The following products are affected by CVE-2025-39964 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Siemens simatic_s7-1500_cpu_1518-4_pn\/dp_mfp_firmware
2 Siemens simatic_s7-1500_cpu_1518f-4_pn\/dp_mfp_firmware
3 Siemens simatic_s7-1500_cpu_1518-4_pn\/dp_mfp
4 Siemens simatic_s7-1500_cpu_1518f-4_pn\/dp_mfp
1 Linux linux_kernel
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 3.1 LOW [email protected]
CVSS 3.1 HIGH 416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS 3.1 MEDIUM [email protected]
Solution
Prevent concurrent writes to af_alg sockets to avoid data interleaving and state inconsistencies.
  • Modify af_alg_sendmsg to disallow concurrent writes.
  • Implement exclusive ownership checks for writing.
  • Apply the provided kernel patch.
  • Update the Linux kernel.
Public PoC/Exploit Available at Github

CVE-2025-39964 has a 2 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-39964 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-39964 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Mirror of https://github.com/nomi-sec/PoC-in-GitHub

Updated: 7 months, 1 week ago
0 stars 0 fork 0 watcher
Born at : Feb. 7, 2026, 10:02 a.m. This repo has been linked 789 different CVEs too.

CVE-2025-39964 EXP

C Makefile

Updated: 10 months ago
0 stars 0 fork 0 watcher
Born at : Nov. 13, 2025, 1:07 p.m. This repo has been linked 1 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-39964 vulnerability anywhere in the article.

  • The Hacker News
CISA Flags Three Linux Kernel Vulnerabilities Exploited in the Wild

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added three security flaws impacting the Linux kernel to its Known Exploited Vulnerabilities (KEV) catalog, citing evidence o ... Read more

Published Date: Sep 19, 2026 (11 hours, 5 minutes ago)
  • TheCyberThrone
CISA KEV Update: Three Linux Kernel Bugs, Acronis Backup and Google Pixel

September 18, 2026 — CISA added three Linux kernel vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog. Two additional vulnerabilities affecting Acronis Backup and Google Pixel were a ... Read more

Published Date: Sep 19, 2026 (15 hours, 20 minutes ago)

The following table lists the changes that have been made to the CVE-2025-39964 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 19, 2026

    Action Type Old Value New Value
    Changed SSVC {'id': 'CVE-2025-39964', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T14:40:05.718549Z'} {'id': 'CVE-2025-39964', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T00:00:00+00:00'}
  • Modified Analysis by [email protected]

    Sep. 18, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
    Removed CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
    Added CWE CWE-362
    Removed CWE NVD-CWE-noinfo
    Added CPE Configuration AND OR *cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518-4_pn/dp_mfp_firmware:*:*:*:*:*:*:*:* versions from (including) 3.1.6 OR cpe:2.3:h:siemens:simatic_s7-1500_cpu_1518-4_pn/dp_mfp:*:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518f-4_pn/dp_mfp_firmware:*:*:*:*:*:*:*:* versions from (including) 3.1.6 OR cpe:2.3:h:siemens:simatic_s7-1500_cpu_1518f-4_pn/dp_mfp:*:*:*:*:*:*:*:*
    Added Reference Type siemens-SADP: https://cert-portal.siemens.com/productcert/html/ssa-019113.html Types: Third Party Advisory
    Added Reference Type CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39964 Types: US Government Resource
  • CVE CISA KEV Update by 9119a7d8-5eab-497f-8521-727c672e3725

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Date Added 2026-09-18
    Added Due Date 2026-09-18
    Added Required Action 2026-09-18
    Added Vulnerability Name 2026-09-18
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39964
    Changed SSVC {'id': 'CVE-2025-39964', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T13:00:36.411880Z'} {'id': 'CVE-2025-39964', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T14:40:05.718549Z'}
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Reference https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce
    Added Reference https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285
    Added Reference https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8
    Added Reference https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042
    Added Reference https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84
    Added Reference https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d
    Added Reference https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9
    Removed Reference https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce
    Removed Reference https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285
    Removed Reference https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8
    Removed Reference https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042
    Removed Reference https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84
    Removed Reference https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d
    Removed Reference https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9
    Removed Reference Type https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8 Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042 Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84 Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9 Types: Patch
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 18, 2026

    Action Type Old Value New Value
    Added CWE CWE-362
    Changed SSVC {'id': 'CVE-2025-39964', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-10T20:40:19.988750Z'} {'id': 'CVE-2025-39964', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T13:00:36.411880Z'}
  • CVE Modified by 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Reference https://cert-portal.siemens.com/productcert/html/ssa-019113.html
    Removed Reference https://cert-portal.siemens.com/productcert/html/ssa-019113.html
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jul. 30, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  • CVE Modified by 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

    Jul. 14, 2026

    Action Type Old Value New Value
    Added Affected [{'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIPLUS S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}]
    Added Reference https://cert-portal.siemens.com/productcert/html/ssa-019113.html
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Jun. 17, 2026

    Action Type Old Value New Value
    Added SSVC {'id': 'CVE-2025-39964', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-10T20:40:19.988750Z'}
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jun. 17, 2026

    Action Type Old Value New Value
    Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '8ff590903d5fc7f5a0a988c38267a3d08e6393a2', 'lessThan': '0f28c4adbc4a97437874c9b669fd7958a8c6d6ce', 'versionType': 'git'}, {'status': 'affected', 'version': '8ff590903d5fc7f5a0a988c38267a3d08e6393a2', 'lessThan': 'e4c1ec11132ec466f7362a95f36a506ce4dc08c9', 'versionType': 'git'}, {'status': 'affected', 'version': '8ff590903d5fc7f5a0a988c38267a3d08e6393a2', 'lessThan': '1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8', 'versionType': 'git'}, {'status': 'affected', 'version': '8ff590903d5fc7f5a0a988c38267a3d08e6393a2', 'lessThan': '7c4491b5644e3a3708f3dbd7591be0a570135b84', 'versionType': 'git'}, {'status': 'affected', 'version': '8ff590903d5fc7f5a0a988c38267a3d08e6393a2', 'lessThan': '9aee87da5572b3a14075f501752e209801160d3d', 'versionType': 'git'}, {'status': 'affected', 'version': '8ff590903d5fc7f5a0a988c38267a3d08e6393a2', 'lessThan': '45bcf60fe49b37daab1acee57b27211ad1574042', 'versionType': 'git'}, {'status': 'affected', 'version': '8ff590903d5fc7f5a0a988c38267a3d08e6393a2', 'lessThan': '1b34cbbf4f011a121ef7b2d7d6e6920a036d5285', 'versionType': 'git'}], 'programFiles': ['crypto/af_alg.c', 'include/crypto/if_alg.h'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.38'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.38', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.245', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.194', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.154', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.108', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.49', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.16.9', 'versionType': 'semver', 'lessThanOrEqual': '6.16.*'}, {'status': 'unaffected', 'version': '6.17', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['crypto/af_alg.c', 'include/crypto/if_alg.h'], 'defaultStatus': 'affected'}]
  • Reanalysis by [email protected]

    Feb. 26, 2026

    Action Type Old Value New Value
  • Initial Analysis by [email protected]

    Feb. 03, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
    Added CWE NVD-CWE-noinfo
    Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.49 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11 up to (excluding) 5.15.194 *cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.16.9 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 up to (excluding) 6.6.108 *cpe:2.3:o:linux:linux_kernel:6.17:rc6:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.16 up to (excluding) 6.1.154 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 2.6.38 up to (excluding) 5.10.245
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9 Types: Patch
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Oct. 13, 2025

    Action Type Old Value New Value
    Added 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.
    Added Reference https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce
    Added Reference https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285
    Added Reference https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8
    Added Reference https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042
    Added Reference https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84
    Added Reference https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d
    Added Reference https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.