CVE-2026-52944
ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE
Description
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.
INFO
Published Date :
June 24, 2026, 10:17 a.m.
Last Modified :
Sept. 14, 2026, 12:17 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Add share-level writable check.
- Add per-handle access check for sparse attribute.
- Ensure file references are not leaked on error.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-52944.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-52944 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-52944
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-52944 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-52944 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Sep. 14, 2026
Action Type Old Value New Value Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/52xxx/CVE-2026-52944.json">CVE-2026-52944</a> Added Reference https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812 Added Reference https://git.kernel.org/stable/c/3a9a0a1c38ef90788f5d7c4b29903c8b220f744a Added Reference https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73 Added Reference https://git.kernel.org/stable/c/c5ab11263e3c89aa7989afc5374ef7743e092fd0 Added Reference https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02 Added Reference https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8 Added Reference https://git.kernel.org/stable/c/ef664475c1bf1a27d45dae6848ca9c9c4d86853f Removed Reference https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812 Removed Reference https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73 Removed Reference https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02 Removed Reference https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8 Removed Reference Type https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812 Types: Patch Removed Reference Type https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73 Types: Patch Removed Reference Type https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02 Types: Patch Removed Reference Type https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8 Types: Patch -
Initial Analysis by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Added CWE NVD-CWE-noinfo Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 7.0.12 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.15 up to (excluding) 6.6.143 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.18.35 Added Reference Type kernel.org: https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8 Types: Patch -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jun. 24, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9', 'lessThan': '3127a884525dc8ca4def73254bfcd3ccef0bf812', 'versionType': 'git'}, {'status': 'affected', 'version': 'e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9', 'lessThan': 'de9eb0b44fa9123170e6245b49638e0e453c10f8', 'versionType': 'git'}, {'status': 'affected', 'version': 'e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9', 'lessThan': 'aef151bcfa494bfe983669de2726734b534adb73', 'versionType': 'git'}, {'status': 'affected', 'version': 'e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9', 'lessThan': 'cc57232cae23c0df91b4a59d0f519141ce9b5b02', 'versionType': 'git'}], 'programFiles': ['fs/smb/server/smb2pdu.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5.15'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.15', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.143', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.18.35', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.0.12', 'versionType': 'semver', 'lessThanOrEqual': '7.0.*'}, {'status': 'unaffected', 'version': '7.1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/server/smb2pdu.c'], 'defaultStatus': 'affected'}] Added Description 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. Added Reference https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812 Added Reference https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73 Added Reference https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02 Added Reference https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8