From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-90263: btrfs: check if root is readonly when setting posix acl
Date: Thu, 17 Sep 2026 17:11:33 +0100 [thread overview]
Message-ID: <2026091746-CVE-2026-90263-e245@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
btrfs: check if root is readonly when setting posix acl
For a filesystem which has btrfs read-only property set to true, all
write operations including acl and xattr should be denied. However, acl
can still be set even if btrfs ro property is true.
This happens because no function on the set_acl code path checks the root
is readonly or not. It was checked in btrfs_setxattr_trans() but got
removed in commit 353c2ea735e4 ("btrfs: remove redundant readonly root
check in btrfs_setxattr_trans")
That commit didn't check if all the callers properly check the root's
read-only flag. A previous fix is commit b51111271b03 ("btrfs: check if
root is readonly while setting security xattr").
Always check if the root is read-only before performing the set acl
operation.
The Linux kernel CVE team has assigned CVE-2026-90263 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.2 with commit 353c2ea735e4b54fb6250861e67b51b1bcb47198 and fixed in 7.2.6 with commit d5602f96ff1e266f069b4d0d94f441050e057e06
Issue introduced in 5.2 with commit 353c2ea735e4b54fb6250861e67b51b1bcb47198 and fixed in 7.3-rc1 with commit 01c2f41fc441f75b3f9326443372faceb1cb6638
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-2026-90263
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:
fs/btrfs/acl.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/d5602f96ff1e266f069b4d0d94f441050e057e06
https://git.kernel.org/stable/c/01c2f41fc441f75b3f9326443372faceb1cb6638
reply other threads:[~2026-09-17 16:22 UTC|newest]
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