CVE-2026-74625: netfilter: bridge: release template ct on non-IP path

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

netfilter: bridge: release template ct on non-IP path

A bridge nftables ct zone set rule can attach a conntrack template to
an skb before nf_ct_bridge_pre() sees it. For non-IPv4 and non-IPv6
EtherTypes, nf_ct_bridge_pre() currently overwrites skb->_nfct with
IP_CT_UNTRACKED without releasing the existing template reference.

That makes the per-cpu template, and any temporary templates allocated
for concurrent use, unreachable and leaks memory until the host runs out
of slab.

Reset the skb conntrack state before marking the frame untracked so the
existing template reference is dropped on the non-IP path.

The Linux kernel CVE team has assigned CVE-2026-74625 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.3 with commit 3c171f496ef57774f8e5d509923372549734877f and fixed in 5.10.265 with commit fc90df37540627d092af770215fb4b7befe9409b
	Issue introduced in 5.3 with commit 3c171f496ef57774f8e5d509923372549734877f and fixed in 5.15.216 with commit daa6e070f8e1e7a4dddec8b64ca37663f8cda917
	Issue introduced in 5.3 with commit 3c171f496ef57774f8e5d509923372549734877f and fixed in 6.1.183 with commit bd7b16494dacf87e9336a1dcfdada83b9e40edd6
	Issue introduced in 5.3 with commit 3c171f496ef57774f8e5d509923372549734877f and fixed in 6.6.152 with commit 6ea88401e10e04e0b3bb7a7adea54932fb60b93b
	Issue introduced in 5.3 with commit 3c171f496ef57774f8e5d509923372549734877f and fixed in 6.12.104 with commit 46d559f00b1ab1d114f92d2f16c5ef0093b3b9dd
	Issue introduced in 5.3 with commit 3c171f496ef57774f8e5d509923372549734877f and fixed in 6.18.45 with commit c58d34fe8b7e47bb0b350a7625023b1261342be5
	Issue introduced in 5.3 with commit 3c171f496ef57774f8e5d509923372549734877f and fixed in 7.1.9 with commit 7cff440d702616022769f2643168d7f9820547a0
	Issue introduced in 5.3 with commit 3c171f496ef57774f8e5d509923372549734877f and fixed in 7.2 with commit d45cc8020d7c0a9f01dee42ff5c40bc14c9af72f

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-2026-74625
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:
	net/bridge/netfilter/nf_conntrack_bridge.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/fc90df37540627d092af770215fb4b7befe9409b
	https://git.kernel.org/stable/c/daa6e070f8e1e7a4dddec8b64ca37663f8cda917
	https://git.kernel.org/stable/c/bd7b16494dacf87e9336a1dcfdada83b9e40edd6
	https://git.kernel.org/stable/c/6ea88401e10e04e0b3bb7a7adea54932fb60b93b
	https://git.kernel.org/stable/c/46d559f00b1ab1d114f92d2f16c5ef0093b3b9dd
	https://git.kernel.org/stable/c/c58d34fe8b7e47bb0b350a7625023b1261342be5
	https://git.kernel.org/stable/c/7cff440d702616022769f2643168d7f9820547a0
	https://git.kernel.org/stable/c/d45cc8020d7c0a9f01dee42ff5c40bc14c9af72f