CVE-2026-90153 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN12-LINUX612-20506700
- published5 Oct 2026
- disclosed17 Sept 2026
Introduced: 17 Sep 2026
NewCVE-2026-90153 (opens in a new tab)How to fix?
Upgrade Debian:12 linux-6.12 to version 6.12.111-1~deb12u1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Debian.
See How to fix? for Debian:12 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: bound smb_check_perm_dacl() ACE walks by DACL size
smb_check_perm_dacl() validates that the DACL fits inside the NT security descriptor, but then bounds its two ACE walks by the remaining NTSD length (acl_size) rather than the DACL's declared size (pdacl_size).
When pdacl->size is smaller than the trailing NTSD buffer, bytes after the declared DACL boundary - still inside the stored security descriptor - are parsed as ACEs during access checks. A crafted DACL can place an access-granting ACE beyond pdacl->size, and the current code accepts it during SMB2_CREATE access validation, while parse_dacl() and smb_inherit_dacl() stop at pdacl_size.
Bound both ACE walks by pdacl_size to match the DACL boundary semantics used elsewhere in the server.
Validation:
- semantic KUnit harness shows the post-boundary ACE is selected before the fix and rejected (EACCES) after it
- linux master (7.2-rc6), x86_64
References
- https://security-tracker.debian.org/tracker/CVE-2026-90153
- https://git.kernel.org/stable/c/79decd88dd3f0d42e7fb0689b1a7853bfa302459
- https://git.kernel.org/stable/c/8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67
- https://git.kernel.org/stable/c/a2051ffe452afad52f580b85a3fd8851933b1e7c
- https://git.kernel.org/stable/c/a29f57a14c939586d84d7fd6a029bd1fd170098f
- https://git.kernel.org/stable/c/a4a307d149327dad5fb25187e1b03cebd1b04de6