CVE-2026-52944 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.12% (2nd percentile)

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  • Snyk IDSNYK-DEBIAN12-LINUX612-20506288
  • published5 Oct 2026
  • disclosed24 Jun 2026

Introduced: 24 Jun 2026

CVE-2026-52944  (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: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE

FSCTL_SET_SPARSE in fsctl_set_sparse() modifies the file's sparse attribute and saves it through xattr without any permission checks.

This exposes two issues:

  1. A client on a read-only share can change the sparse attribute on files it opened, even though the share is read-only. Other FSCTL write operations already check test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE), but FSCTL_SET_SPARSE does not.

  2. Even on writable shares, clients without FILE_WRITE_DATA or FILE_WRITE_ATTRIBUTES access should not modify the sparse attribute. Similar handle-level checks exist in other functions but are missing here.

Add both share-level writable check and per-handle access check. Use goto out on error to avoid leaking file references.

CVSS Base Scores

version 3.1