CVE-2025-21648: netfilter: conntrack: clamp maximum hashtable size to INT_MAX

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-01-19 · updated 2026-10-15

Description

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.

Affected products

Linux kernel: from 4.7.1 before 5.10.234; from 5.11 before 5.15.177; from 5.16 before 6.1.125; from 6.2 before 6.6.72; from 6.7 before 6.12.10; 4.7, 6.13-rc1, 6.13-rc2, 6.13-rc3, 6.13-rc4, 6.13-rc5 (+1) — fixed in 5.10.234, 5.15.177, 6.1.125, 6.12.10, 6.6.72

How to fix

Upgrade to a fixed version: Linux kernel 5.10.234, 5.15.177, 6.1.125, 6.12.10. Check the vendor advisory for mitigations.

References

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