ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE (Linux Linux)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.12 % · percentile 2 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- Linux
- NVD status
- Modified
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.
References
- https://git.kernel.org/stable/c/ef664475c1bf1a27d45dae6848ca9c9c4d86853f
- https://git.kernel.org/stable/c/3a9a0a1c38ef90788f5d7c4b29903c8b220f744a
- https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812
- https://git.kernel.org/stable/c/c5ab11263e3c89aa7989afc5374ef7743e092fd0
- https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8
- https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73
- https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | NVD · nvd@nist.gov (Primary) |
European references
- ENISA EUVD · EUVD-2026-38734
- GCVE · GCVE-0-2026-52944
CERT-FR advisories
- CERTFR-2026-AVI-1375 — Multiples vulnérabilités dans le noyau Linux de Debian LTS · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1333 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1289 — Multiples vulnérabilités dans le noyau Linux de Debian LTS · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1286 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1253 — Multiples vulnérabilités dans le noyau Linux de Debian · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1252 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1229 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1162 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1066 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0954 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0926 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*≥ 5.15 < 6.6.143cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*≥ 6.7 < 6.18.35cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*≥ 6.19 < 7.0.12cpe: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:*:*:*:*:*:*
Affected products
| Product | Versions |
|---|---|
| Linux · Linux | affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < ef664475c1bf1a27d45dae6848ca9c9c4d86853f ; affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 3a9a0a1c38ef90788f5d7c4b29903c8b220f744a ; affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 3127a884525dc8ca4def73254bfcd3ccef0bf812 ; affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < c5ab11263e3c89aa7989afc5374ef7743e092fd0 ; affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < de9eb0b44fa9123170e6245b49638e0e453c10f8 ; affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < aef151bcfa494bfe983669de2726734b534adb73 |
| Linux · Linux | affected 5.15 ; unaffected 0 < 5.15 ; unaffected 5.15.221 ≤ 5.15.* ; unaffected 6.1.188 ≤ 6.1.* ; unaffected 6.6.143 ≤ 6.6.* ; unaffected 6.12.110 ≤ 6.12.* |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |