linux-cve-announce - CVE-2026-22999: net/sched: sch_qfq: do not free existing class in qfq_change

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Message-ID: <2026012533-CVE-2026-22999-c098@gregkh>
Date: Sun, 25 Jan 2026 15:36:35 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-22999: net/sched: sch_qfq: do not free existing class in qfq_change_class()

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

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

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

net/sched: sch_qfq: do not free existing class in qfq_change_class()

Fixes qfq_change_class() error case.

cl->qdisc and cl should only be freed if a new class and qdisc
were allocated, or we risk various UAF.

The Linux kernel CVE team has assigned CVE-2026-22999 to this issue.


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

	Issue introduced in 3.8 with commit 462dbc9101acd38e92eda93c0726857517a24bbd and fixed in 6.12.67 with commit 362e269bb03f7076ba9990e518aeddb898232e50
	Issue introduced in 3.8 with commit 462dbc9101acd38e92eda93c0726857517a24bbd and fixed in 6.18.7 with commit e9d8f11652fa08c647bf7bba7dd8163241a332cd
	Issue introduced in 3.8 with commit 462dbc9101acd38e92eda93c0726857517a24bbd and fixed in 6.19-rc6 with commit 3879cffd9d07aa0377c4b8835c4f64b4fb24ac78

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-2026-22999
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/sched/sch_qfq.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/362e269bb03f7076ba9990e518aeddb898232e50
	https://git.kernel.org/stable/c/e9d8f11652fa08c647bf7bba7dd8163241a332cd
	https://git.kernel.org/stable/c/3879cffd9d07aa0377c4b8835c4f64b4fb24ac78