🛡️ CVE-2025-21637 on Debian — linux

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

In the Linux kernel, the following vulnerability has been resolved: sctp: sysctl: udp_port: avoid using current->nsproxy As mentioned in a previous commit of this series, using the 'net' structure via 'current' is not recommended for different reasons: - Inconsistency: getting info from the reader's/writer's netns vs only from the opener's netns. - current->nsproxy can be NULL in some cases, resulting in an 'Oops' (null-ptr-deref), e.g. when the current task is exiting, as spotted by syzbot [1] using acct(2). The 'net' structure can be obtained from the table->data using container_of(). Note that table->data could also be used directly, but that would increase the size of this fix, while 'sctp.ctl_sock' still needs to be retrieved from 'net' structure.

Distribution advisory

This page covers CVE-2025-21637 as tracked by Debian, for the package linux. The fix is available in version 6.12.10-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software

DEBIAN-CVE-2025-21637 is recorded against 2 packages.

linux (fixed in 6.12.10-1)
linux-6.1 (fixed in 6.1.128-1~deb11u1)

Timeline and source

Published on 19 January 2025 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2025-21637 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

BellSoft Base record Ubuntu

Details

Severity Unknown

CVSS Score N/A

CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2025-01-19

Updated 2026-08-12

Modified 2026-08-04

Fix URL N/A

Affected Packages

Software	From version	Fixed in
linux	—	6.12.10-1
linux-6.1	—	6.1.128-1~deb11u1

References

ADVISORY https://security-tracker.debian.org/tracker/CVE-2025-21637

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