CVE-2026-80846: xfrm: drop ESP-in-TCP packets with no ingress device

CVE-2026-80846: xfrm: drop ESP-in-TCP packets with no ingress device

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

xfrm: drop ESP-in-TCP packets with no ingress device

ESP-in-TCP receives records through the TCP strparser. handle_esp()
restores skb->dev from the saved skb_iif before passing the packet into
the XFRM input path.

Queued TCP data can be processed after the original ingress device has
been removed, for example during veth or net namespace teardown. In that
case dev_get_by_index_rcu() returns NULL. The XFRM IPv4 and IPv6 input
paths both expect skb->dev to be valid while building the route lookup,
so queued ESP-in-TCP data can dereference a NULL device.

Drop the packet if the saved ingress device can no longer be resolved.
Such a packet can no longer be routed through the normal XFRM receive
path, and this preserves the existing behaviour for packets whose ingress
device still exists.

The Linux kernel CVE team has assigned CVE-2026-80846 to this issue.


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

	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 5.10.269 with commit 239d0f71af09dc2029fd4d730cb24b8c83aaa43a
	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 5.15.220 with commit f00235f9d12301183d61f75fbe4105506f3e5140
	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 6.1.187 with commit 6af5cdb03819a5ce6e945992635c6c5e91045367
	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 6.6.156 with commit 2dd1609cadff46c4b20ce53b91ab9cce1380456a
	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 6.12.108 with commit c296d25efbc840be24de83f56d43bc47e714ace9
	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 6.18.49 with commit 328e40aa774b446969c69b654c52a051a95af8a1
	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 7.1.13 with commit 7911e0236616487b89db6bd3ba3f408abd10eb23
	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 7.2.3 with commit 943d95233b8b4a88994e244fcf466f8c403d63f1
	Issue introduced in 5.6 with commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593 and fixed in 7.3-rc1 with commit e1d7c5ac1c246ce5775f604515de0a59fbf2116e

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-2026-80846
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/xfrm/espintcp.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/239d0f71af09dc2029fd4d730cb24b8c83aaa43a
	https://git.kernel.org/stable/c/f00235f9d12301183d61f75fbe4105506f3e5140
	https://git.kernel.org/stable/c/6af5cdb03819a5ce6e945992635c6c5e91045367
	https://git.kernel.org/stable/c/2dd1609cadff46c4b20ce53b91ab9cce1380456a
	https://git.kernel.org/stable/c/c296d25efbc840be24de83f56d43bc47e714ace9
	https://git.kernel.org/stable/c/328e40aa774b446969c69b654c52a051a95af8a1
	https://git.kernel.org/stable/c/7911e0236616487b89db6bd3ba3f408abd10eb23
	https://git.kernel.org/stable/c/943d95233b8b4a88994e244fcf466f8c403d63f1
	https://git.kernel.org/stable/c/e1d7c5ac1c246ce5775f604515de0a59fbf2116e