From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-72382: ksmbd: reject undersized DACLs before parsing ACEs
Date: Sat, 15 Aug 2026 15:07:41 +0900 [thread overview]
Message-ID: <2026081518-CVE-2026-72382-aa5f@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: reject undersized DACLs before parsing ACEs
parse_dacl() limits the attacker-controlled ACE count by comparing it
with the number of minimal ACEs that fit in the DACL size. The DACL size
field is 16 bits, but the expression subtracts sizeof(struct smb_acl).
Because sizeof() is unsigned, a DACL size smaller than the ACL header
underflows to a large size_t.
A malicious client can reach this with:
SMB2_SET_INFO (InfoType=SMB2_O_INFO_SECURITY)
-> smb2_set_info_sec()
-> set_info_sec()
-> parse_sec_desc()
-> parse_dacl()
-> init_acl_state(..., 0xffff)
-> init_acl_state(..., 0xffff)
-> kmalloc_objs(..., 0xffff)
Thus a malformed security descriptor can make num_aces pass the guard
and drive large temporary ACL state and pointer-array allocations.
Reject DACLs smaller than struct smb_acl before doing the subtraction,
so the ACE count check cannot be bypassed by the underflow.
The Linux kernel CVE team has assigned CVE-2026-72382 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 6.6.145 with commit 16fb65ec15fe7c90f50a2115854bfd9a032d4023
Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 6.12.97 with commit 282847c0cf22f2e961155ac8e42f6eeab7e16049
Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 6.18.40 with commit d020e7f27bf65eecd3805404702f716b2b6d9e73
Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 7.1.5 with commit 15a9e9b8f7f5d7f380ae54c6f5bcbc0bdcb0f3cd
Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 7.2-rc2 with commit 60908f7ebcd9b6cde74ad5711fab0f49c7970949
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-2026-72382
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/smb/server/smbacl.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/16fb65ec15fe7c90f50a2115854bfd9a032d4023
https://git.kernel.org/stable/c/282847c0cf22f2e961155ac8e42f6eeab7e16049
https://git.kernel.org/stable/c/d020e7f27bf65eecd3805404702f716b2b6d9e73
https://git.kernel.org/stable/c/15a9e9b8f7f5d7f380ae54c6f5bcbc0bdcb0f3cd
https://git.kernel.org/stable/c/60908f7ebcd9b6cde74ad5711fab0f49c7970949
reply other threads:[~2026-08-15 6:27 UTC|newest]
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