🛡️ CVE-2025-21648 — kernel

🟡 CVSS 5.5 — Medium ✅ No Known Exploit NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

netfilter: conntrack: clamp maximum hashtable size to INT_MAX

In the Linux kernel, the following vulnerability has been resolved:

netfilter: conntrack: clamp maximum hashtable size to INT_MAX

Use INT_MAX as maximum size for the conntrack hashtable. Otherwise, it

is possible to hit WARN_ON_ONCE in __kvmalloc_node_noprof() when

resizing hashtable because __GFP_NOWARN is unset. See:

0708a0afe291 ("mm: Consider __GFP_NOWARN flag for oversized kvmalloc() calls")

Note: hashtable resize is only possible from init_netns.

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

CVE-2025-21648 is recorded against 2 packages.

  • kernel (from 6.7.0 up to 6.12.10)
  • linux-kernel

Timeline and source

Published on 19 January 2025 and last revised on 16 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

cert-portal.siemens.com (Web)
cert-portal.siemens.com (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
lists.debian.org (Web)
lists.debian.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2025-21648 on other distributions

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

Details

Severity Medium
CVSS Score 5.5
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 NVD
Published 2025-01-19
Updated 2026-08-12
Modified 2026-07-16

Affected Packages

Software From version Fixed in
kernel 6.7.0 6.12.10
linux-kernel — —

References

Similar Threats

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