CVE-2026-72418netfilter: nf_conncount: prevent connlimit drops for early confirmed ct
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | 460c112e1d887b58b06b56e8e0230058906ff2c3 builds before 000ac6830b56499d6b65fd91486ce6689eb02be4; from 53bc0ac47f4f7621c991807bc90e01df49561ac8 before cbe2d14a7c5b1fc71821fbfee5c4963917411e92; from ca8b4d1d6304a84ce2016fa2fe9a114b9607b839 before 3793d24de224943e0a6016bbeffb6f5c4cea2e3d; from 8286c02fe9100330475331253fc590f047963f90 before abef7f817217fcb62c11821d6b895063eadb2828; from b29ddccf36946a90323486221f39e9f88cc01b8e before ebfe8249ba79e4ff0f1e3aad8787b992ef27f026; from 77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e before 329f2626ee5cb8fafdf6b58b624311529c57cb45; from 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e before be52572c6d55f677ba76869d3c63805c0d4891a3; from 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e before c8b6f36f766991e3ebebec6596daee4b04dcbc49; and 8 more ranges | CNA record |
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
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.