linux-cve-announce - CVE-2025-40135: ipv6: use RCU in ip6

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Message-ID: <2025111255-CVE-2025-40135-67ca@gregkh>
Date: Wed, 12 Nov 2025 19:24:11 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40135: ipv6: use RCU in ip6_xmit()

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

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

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

ipv6: use RCU in ip6_xmit()

Use RCU in ip6_xmit() in order to use dst_dev_rcu() to prevent
possible UAF.

The Linux kernel CVE team has assigned CVE-2025-40135 to this issue.


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

	Issue introduced in 4.13 with commit 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36 and fixed in 6.17.3 with commit f7f9e924f23684b4b23cd9f976cceab24a968e34
	Issue introduced in 4.13 with commit 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36 and fixed in 6.18-rc1 with commit 9085e56501d93af9f2d7bd16f7fcfacdde47b99c

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-2025-40135
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/ipv6/ip6_output.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/f7f9e924f23684b4b23cd9f976cceab24a968e34
	https://git.kernel.org/stable/c/9085e56501d93af9f2d7bd16f7fcfacdde47b99c