CVE-2025-39964
Description
A race condition was found in the Linux kernel cryptographic user API, AF_ALG in the way concurrent writes to the same AF_ALG socket are handled. Interleaved data and inconsistent internal socket state may result.
A local user could use this flaw to crash the system or corrupt cryptographic operation results, causing a denial of service or data integrity issues.
Statement
The AF_ALG datapath allowed two writers on the same socket, causing request payloads to interleave unpredictably and leaving the per-socket context inconsistent. The fix introduces an exclusive write ownership (ctx->write) so that only one writer can issue sendmsg() at a time, preventing state corruption.
Mitigation
To mitigate this issue, prevent module af_alg from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | 3.3 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | High |
| Integrity Impact | None | None | High |
| Availability Impact | High | Low | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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