From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89743: misc: nsm: bound the device-reported response length
Date: Fri, 11 Sep 2026 21:47:12 +0200 [thread overview]
Message-ID: <2026091105-CVE-2026-89743-34df@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
misc: nsm: bound the device-reported response length
nsm_sendrecv_msg_locked() stores the virtqueue used-ring length reported
by the NSM device into msg->resp.len without bounding it to the response
buffer. A malicious or buggy backend can report a length larger than the
response buffer; parse_resp_raw() then copies that many bytes out of the
fixed buffer to user space, disclosing adjacent kernel heap (an
out-of-bounds read). The request path already floors its length in
fill_req_raw(); the response path lacks the symmetric check.
Clamp the stored length to the size of the response buffer. Well-behaved
devices report no more than the posted buffer size, so conforming traffic
is unaffected.
The Linux kernel CVE team has assigned CVE-2026-89743 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.8 with commit b9873755a6c8ccfce79094c4dce9efa3ecb1a749 and fixed in 6.12.109 with commit 339f19b9a6171289b0e797deb8bda80b9a1fcc30
Issue introduced in 6.8 with commit b9873755a6c8ccfce79094c4dce9efa3ecb1a749 and fixed in 6.18.50 with commit 29e634a18957acda11383a15ab98a91c4ae9e294
Issue introduced in 6.8 with commit b9873755a6c8ccfce79094c4dce9efa3ecb1a749 and fixed in 7.2.4 with commit 2aa0fb9c96f894a9c179a48e7522ea6705800adf
Issue introduced in 6.8 with commit b9873755a6c8ccfce79094c4dce9efa3ecb1a749 and fixed in 7.3-rc1 with commit 808e530654a5354e6df78863a5d61e4d44e67235
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-2026-89743
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:
drivers/misc/nsm.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/339f19b9a6171289b0e797deb8bda80b9a1fcc30
https://git.kernel.org/stable/c/29e634a18957acda11383a15ab98a91c4ae9e294
https://git.kernel.org/stable/c/2aa0fb9c96f894a9c179a48e7522ea6705800adf
https://git.kernel.org/stable/c/808e530654a5354e6df78863a5d61e4d44e67235
reply other threads:[~2026-09-11 20:07 UTC|newest]
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