CVE-2026-52944: ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE
Noroxi assessment
Priority: Monitor (action score 22/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
- Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: Linux Linux 3127a884525dc8ca4def73254bfcd3ccef0bf812, 3a9a0a1c38ef90788f5d7c4b29903c8b220f744a, aef151bcfa494bfe983669de2726734b534adb73; azl3 kernel 6.6.141.1-1 on Azure Linux 3.0 6.6.143.1-1.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to Linux Linux 3127a884525dc8ca4def73254bfcd3ccef0bf812, 3a9a0a1c38ef90788f5d7c4b29903c8b220f744a, aef151bcfa494bfe983669de2726734b534adb73; azl3 kernel 6.6.141.1-1 on Azure Linux 3.0 6.6.143.1-1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- Published
- Jun 24, 2026
- Updated
- Sep 14, 2026
- EPSS
- 0.1% · 1th percentile
- CWE
- —
Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 22 / 40 · 5.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.1%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| linux | linux kernel | cpe:2.3:o:linux:linux_kernel |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- linux linux kernel5.15 and later · before 6.6.143
- linux linux kernel6.7 and later · before 6.18.35
- linux linux kernel6.19 and later · before 7.0.12
- linux linux kernel7.1
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- 5.15affected
- e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before ef664475c1bf1a27d45dae6848ca9c9c4d86853faffected · git
- e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before 3a9a0a1c38ef90788f5d7c4b29903c8b220f744aaffected · git
- e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before 3127a884525dc8ca4def73254bfcd3ccef0bf812affected · git
- e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before c5ab11263e3c89aa7989afc5374ef7743e092fd0affected · git
- e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before de9eb0b44fa9123170e6245b49638e0e453c10f8affected · git
- e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before aef151bcfa494bfe983669de2726734b534adb73affected · git
- e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before cc57232cae23c0df91b4a59d0f519141ce9b5b02affected · git
- before 5.15not affected · semver
- 5.15.221 and later · up to and including 5.15.*not affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | linux | before 6.1.190-1 | 6.1.190-1 |
| Debian:12 | linux-6.12 | before 6.12.111-1~deb12u1 | 6.12.111-1~deb12u1 |
| Debian:13 | linux | before 6.12.111-1 | 6.12.111-1 |
| Debian:14 | linux | before 7.0.12-1 | 7.0.12-1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV90Now
- CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV89Now
- CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV85Now
Published before and after this one in the same product
- ← EarlierCVE-2026-52939Jun 24, 2026 · net/rds: fix NULL deref in rds_ib_send_cqe_handler() on masked atomic completion22Monitor
- ← EarlierCVE-2026-52940Jun 24, 2026 · tun: zero the whole vnet header in tun_put_user()22Monitor
- Later →CVE-2026-52912Jun 24, 2026 · netfilter: nf_queue: hold bridge skb->dev while queued31Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 3127a884525dc8ca4def73254bfcd3ccef0bf812 | Vendor (CNA) |
| Linux Linux | 3a9a0a1c38ef90788f5d7c4b29903c8b220f744a | Vendor (CNA) |
| Linux Linux | aef151bcfa494bfe983669de2726734b534adb73 | Vendor (CNA) |
| Linux Linux | c5ab11263e3c89aa7989afc5374ef7743e092fd0 | Vendor (CNA) |
| Linux Linux | cc57232cae23c0df91b4a59d0f519141ce9b5b02 | Vendor (CNA) |
| Linux Linux | de9eb0b44fa9123170e6245b49638e0e453c10f8 | Vendor (CNA) |
| Linux Linux | ef664475c1bf1a27d45dae6848ca9c9c4d86853f | Vendor (CNA) |
| azl3 kernel 6.6.141.1-1 on Azure Linux 3.0 | 6.6.143.1-1 · CBL-Mariner Releases | Microsoft (MSRC) |
| debian:linux | 6.1.190-1 · Debian:12 | Package registry (OSV) |
| debian:linux | 6.12.111-1 · Debian:13 | Package registry (OSV) |
| debian:linux-6.12 | 6.12.111-1~deb12u1 · Debian:12 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-26-0440 · Jun 25, 2026(Linux Kernel Güvenlik Bildirimi)
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
—
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (6 more)Show less
- git.kernel.org/stable/c/3a9a0a1c38ef90788f5d7c4b29903c8b220f744a
- git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73
- git.kernel.org/stable/c/c5ab11263e3c89aa7989afc5374ef7743e092fd0
- git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02
- git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8
- git.kernel.org/stable/c/ef664475c1bf1a27d45dae6848ca9c9c4d86853f
Vendor advisories and official records. Exploit/PoC links are deliberately left out.