From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-74255: tipc: fix UAF in tipc_l2_send_msg()
Date: Sat, 15 Aug 2026 15:09:42 +0900 [thread overview]
Message-ID: <2026081541-CVE-2026-74255-caef@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
tipc: fix UAF in tipc_l2_send_msg()
Syzbot reported a slab-use-after-free in ipvlan_hard_header() when
called from tipc_l2_send_msg().
The root cause is that tipc_disable_l2_media() calls synchronize_net()
while b->media_ptr is still valid. This allows concurrent RCU readers
to obtain the device pointer after synchronize_net() has finished.
The pointer is cleared later in bearer_disable(), but without any
subsequent synchronization, allowing the device to be freed while
still in use by readers.
Fix this by clearing b->media_ptr in tipc_disable_l2_media() before
calling synchronize_net().
This is safe to do now because the call order in bearer_disable()
was reversed in 0d051bf93c06 ("tipc: make bearer packet filtering generic")
to call tipc_node_delete_links() (which needs the pointer) before
disable_media().
https: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u
The Linux kernel CVE team has assigned CVE-2026-74255 to this issue.
Affected and fixed versions
===========================
Issue introduced in 4.4 with commit 282b3a056225b35024246f63feb91d769d714dad and fixed in 5.10.261 with commit 609ced2301be1df7e7ed2ef47d1d916674e6ba3b
Issue introduced in 4.4 with commit 282b3a056225b35024246f63feb91d769d714dad and fixed in 5.15.212 with commit 71aafa16d79b107b33837f60b6cbc7d0cb8c5708
Issue introduced in 4.4 with commit 282b3a056225b35024246f63feb91d769d714dad and fixed in 6.1.178 with commit f4002f1c669cc02e3763f479fc25ff1dfa9e2420
Issue introduced in 4.4 with commit 282b3a056225b35024246f63feb91d769d714dad and fixed in 6.6.145 with commit 50ff092633b06382e5091dd5b093ce943d4ac2f9
Issue introduced in 4.4 with commit 282b3a056225b35024246f63feb91d769d714dad and fixed in 6.12.97 with commit aef12b5ce793dea6b3a97a58fd0f946000ae8945
Issue introduced in 4.4 with commit 282b3a056225b35024246f63feb91d769d714dad and fixed in 6.18.40 with commit 0d8a12d7143126afdf9fbe2e3d438650dd6603ed
Issue introduced in 4.4 with commit 282b3a056225b35024246f63feb91d769d714dad and fixed in 7.1.5 with commit 35e0297a93c3c34a3924eeef816c03504e3ab5c5
Issue introduced in 4.4 with commit 282b3a056225b35024246f63feb91d769d714dad and fixed in 7.2-rc1 with commit f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6
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-2026-74255
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/tipc/bearer.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/609ced2301be1df7e7ed2ef47d1d916674e6ba3b
https://git.kernel.org/stable/c/71aafa16d79b107b33837f60b6cbc7d0cb8c5708
https://git.kernel.org/stable/c/f4002f1c669cc02e3763f479fc25ff1dfa9e2420
https://git.kernel.org/stable/c/50ff092633b06382e5091dd5b093ce943d4ac2f9
https://git.kernel.org/stable/c/aef12b5ce793dea6b3a97a58fd0f946000ae8945
https://git.kernel.org/stable/c/0d8a12d7143126afdf9fbe2e3d438650dd6603ed
https://git.kernel.org/stable/c/35e0297a93c3c34a3924eeef816c03504e3ab5c5
https://git.kernel.org/stable/c/f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6
reply other threads:[~2026-08-15 6:33 UTC|newest]
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