From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-74290: net/sched: cls_flow: Dont expose folded kernel pointers
Date: Sat, 15 Aug 2026 15:10:17 +0900 [thread overview]
Message-ID: <2026081547-CVE-2026-74290-9a3d@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
net/sched: cls_flow: Dont expose folded kernel pointers
The flow classifier falls back to addr_fold() for fields that are missing
from packet headers. In map mode, userspace controls mask, xor, rshift,
addend and divisor, and can observe the resulting classid through class
statistics. This allows a tc classifier in a user/network namespace to
recover the 32-bit folded value of skb->sk, skb_dst() or skb_nfct().
Align with standard kernel practices for pointer hashing and replace the
XOR folding with a keyed siphash (which is cryptographically secure)
The Linux kernel CVE team has assigned CVE-2026-74290 to this issue.
Affected and fixed versions
===========================
Issue introduced in 2.6.25 with commit e5dfb815181fcb186d6080ac3a091eadff2d98fe and fixed in 6.1.178 with commit 19f2ecf8ea564562c7e7a919cf38068dd9aa1c96
Issue introduced in 2.6.25 with commit e5dfb815181fcb186d6080ac3a091eadff2d98fe and fixed in 6.6.145 with commit 3d054001860270748405a3f9270c5fa0bf7ffc19
Issue introduced in 2.6.25 with commit e5dfb815181fcb186d6080ac3a091eadff2d98fe and fixed in 6.12.97 with commit fb31fbe51c233f3bf47021121f63d2e42cac2d08
Issue introduced in 2.6.25 with commit e5dfb815181fcb186d6080ac3a091eadff2d98fe and fixed in 6.18.40 with commit 0a8b5b74f0e6b6b9ce453bcfa4baa502c4c7577a
Issue introduced in 2.6.25 with commit e5dfb815181fcb186d6080ac3a091eadff2d98fe and fixed in 7.1.5 with commit 6151159618198675e01c391676e579738286c135
Issue introduced in 2.6.25 with commit e5dfb815181fcb186d6080ac3a091eadff2d98fe and fixed in 7.2-rc1 with commit f294fc71c4a0fa4964f6428a1b4e7929c1d83125
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-2026-74290
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/cls_flow.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/19f2ecf8ea564562c7e7a919cf38068dd9aa1c96
https://git.kernel.org/stable/c/3d054001860270748405a3f9270c5fa0bf7ffc19
https://git.kernel.org/stable/c/fb31fbe51c233f3bf47021121f63d2e42cac2d08
https://git.kernel.org/stable/c/0a8b5b74f0e6b6b9ce453bcfa4baa502c4c7577a
https://git.kernel.org/stable/c/6151159618198675e01c391676e579738286c135
https://git.kernel.org/stable/c/f294fc71c4a0fa4964f6428a1b4e7929c1d83125
reply other threads:[~2026-08-15 6:35 UTC|newest]
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