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.

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4379-1 linux-6.1 security update
Debian DLA Debian DLA DLA-4404-1 linux security update
Debian DSA Debian DSA DSA-6053-1 linux security update
Ubuntu USN Ubuntu USN USN-7907-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7907-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7907-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7907-4 Linux kernel (GCP FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7921-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7922-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7922-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7928-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7928-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7928-3 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7907-5 Linux kernel kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7931-3 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7934-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7935-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7936-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7937-1 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7938-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7939-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7939-2 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7940-1 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7921-2 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7922-3 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7928-4 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7931-4 Linux kernel (Xilinx) vulnerabilities
Ubuntu USN Ubuntu USN USN-7922-4 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7928-5 Linux kernel (KVM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7931-5 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7940-2 Linux kernel (Azure, N-Series) vulnerabilities
Ubuntu USN Ubuntu USN USN-7922-5 Linux kernel (IoT) vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 03 Feb 2026 14:30:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
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:6.17:rc6:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

cvssV3_1

{'score': 3.3, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L'}


Mon, 20 Oct 2025 16:15:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Tue, 14 Oct 2025 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate


Mon, 13 Oct 2025 14:00:00 +0000

Type Values Removed Values 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.
Title crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-10-13T13:48:30.334Z

Reserved: 2025-04-16T07:20:57.149Z

Link: CVE-2025-39964

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2025-10-13T14:15:34.737

Modified: 2026-02-26T23:05:10.840

Link: CVE-2025-39964

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-10-13T00:00:00Z

Links: CVE-2025-39964 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-10-20T16:13:28Z

Weaknesses