From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-45860: netfilter: nf_conncount: increase the connection clean up limit to 64
Date: Wed, 27 May 2026 14:18:22 +0200 [thread overview]
Message-ID: <2026052710-CVE-2026-45860-d52c@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conncount: increase the connection clean up limit to 64
After the optimization to only perform one GC per jiffy, a new problem
was introduced. If more than 8 new connections are tracked per jiffy the
list won't be cleaned up fast enough possibly reaching the limit
wrongly.
In order to prevent this issue, only skip the GC if it was already
triggered during the same jiffy and the increment is lower than the
clean up limit. In addition, increase the clean up limit to 64
connections to avoid triggering GC too often and do more effective GCs.
This has been tested using a HTTP server and several
performance tools while having nft_connlimit/xt_connlimit or OVS limit
configured.
Output of slowhttptest + OVS limit at 52000 connections:
slow HTTP test status on 340th second:
initializing: 0
pending: 432
connected: 51998
error: 0
closed: 0
service available: YES
The Linux kernel CVE team has assigned CVE-2026-45860 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.10.248 with commit f106694733c66a48740c25bc4e212e9b2ea364ce and fixed in 5.10.252 with commit a5c9e14e0e8923218ae881d5e78c990c07694966
Issue introduced in 5.15.198 with commit be69850b461e7b491d87a22e33ab76fdd04b725e and fixed in 5.15.202 with commit 13eede458fdf231f1bf96a398feea4ad1553f14c
Issue introduced in 5.19 with commit d265929930e2ffafc744c0ae05fb70acd53be1ee and fixed in 6.1.165 with commit fa85432d58c8e74b39333edbf8d28df2985dfc79
Issue introduced in 5.19 with commit d265929930e2ffafc744c0ae05fb70acd53be1ee and fixed in 6.6.128 with commit 0792ad077d776c2dcf20f0484e2461ded1b77a24
Issue introduced in 5.19 with commit d265929930e2ffafc744c0ae05fb70acd53be1ee and fixed in 6.12.75 with commit 3d0994ed0aa1fc0a2c5e620b765e8defdd021bff
Issue introduced in 5.19 with commit d265929930e2ffafc744c0ae05fb70acd53be1ee and fixed in 6.18.14 with commit 6e5fa7add3e76da068a478d905be64be8fa4e80a
Issue introduced in 5.19 with commit d265929930e2ffafc744c0ae05fb70acd53be1ee and fixed in 6.19.4 with commit 0af0812baf2d363176c9b76fc07e33f13aede8db
Issue introduced in 5.19 with commit d265929930e2ffafc744c0ae05fb70acd53be1ee and fixed in 7.0 with commit 21d033e472735ecec677f1ae46d6740b5e47a4f3
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2026-45860
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
include/net/netfilter/nf_conntrack_count.h
net/netfilter/nf_conncount.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/a5c9e14e0e8923218ae881d5e78c990c07694966
https://git.kernel.org/stable/c/13eede458fdf231f1bf96a398feea4ad1553f14c
https://git.kernel.org/stable/c/fa85432d58c8e74b39333edbf8d28df2985dfc79
https://git.kernel.org/stable/c/0792ad077d776c2dcf20f0484e2461ded1b77a24
https://git.kernel.org/stable/c/3d0994ed0aa1fc0a2c5e620b765e8defdd021bff
https://git.kernel.org/stable/c/6e5fa7add3e76da068a478d905be64be8fa4e80a
https://git.kernel.org/stable/c/0af0812baf2d363176c9b76fc07e33f13aede8db
https://git.kernel.org/stable/c/21d033e472735ecec677f1ae46d6740b5e47a4f3
reply other threads:[~2026-05-27 12:20 UTC|newest]
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