CVE-2026-52944In 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() modifie…
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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
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Sep 14, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
linux linux_kernel linux:linux_kernel | from 5.15 before 6.6.143; from 6.7 before 6.18.35; from 6.19 before 7.0.12; 7.1; 7.1; 7.1; 7.1; 7.1 | NVD |
References
- https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812patch
- https://git.kernel.org/stable/c/3a9a0a1c38ef90788f5d7c4b29903c8b220f744a
- https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73patch
- https://git.kernel.org/stable/c/c5ab11263e3c89aa7989afc5374ef7743e092fd0
- https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02patch
- https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8patch
- https://git.kernel.org/stable/c/ef664475c1bf1a27d45dae6848ca9c9c4d86853f
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.