smb/client: flush dirty data before punching a hole
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 5 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: smb/client: flush dirty data before punching a hole Punching a hole after a large buffered write may leave the range reported as data. Reproduce it with: xfs_io -f \ -c "pwrite -b 3m -S 0x61 0 3m" \ -c "fpunch 1m 1m" \ -c "seek -h 0" \ -c "seek -d 1m" \ /mnt/test/repro Punching 1 MiB at offset 1 MiB should produce: 0 1 MiB 2 MiB 3 MiB | DATA | HOLE | DATA | EOF Instead, the entire file is reported as data. SEEK_HOLE(0) returns EOF, and SEEK_DATA(1M) returns 1M. This happens because a dirty folio spanning the punched range can be written back after the punch and refill the hole. Fix this by flushing and waiting for dirty data in the punched range before invalidating the page cache and issuing FSCTL_SET_ZERO_DATA. The xfstests generic/539 pass against Samba/ksmbd with this change.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.158, 6.12.111, 6.18.53, 7.2
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 2 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-02 Threatist record created from CVE-2026-93794
- 2026-10-03 Alias added: GHSA-5fcw-5g57-rhgg
- 2026-10-03 Fix available: Linux/Linux@216e469586057c29409e4ef8311d282388c6e251, Linux/[email protected] · CNA
- 2026-10-03 1 new reference · CNA
- 2026-10-30 Fix available: Linux/Linux@0c9fcab9bf1ef3516983f3de05a19c5658c7a01e, Linux/[email protected] · CNA
- 2026-10-30 1 new reference · CNA
- 2026-11-07 Affected versions changed · Red Hat
References
Other 5
- https://git.kernel.org/stable/c/0c9fcab9bf1ef3516983f3de05a19c5658c7a01e
- https://git.kernel.org/stable/c/216e469586057c29409e4ef8311d282388c6e251
- https://git.kernel.org/stable/c/6c265aca08155e519a8f6f6071c59dff4f535f70
- https://git.kernel.org/stable/c/39562a56cdb515f6635c3e7bfe6629439b18a169
- https://git.kernel.org/stable/c/d7d2adcd022baade5cab65ca492ce63421ce3a6e
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Sources
- CVE-2026-93794 · CVE Program
- CVE-2026-93794 · NVD
- FIRST EPSS
- GHSA-5fcw-5g57-rhgg · GitHub Advisory Database · CC BY 4.0
- CVE-2026-93794 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences