ksmbd: use opener credentials for delete-on-close
Affects the Linux kernel ksmbd server in 5.15.0 to before 6.6.145, 6.7.0 to before 6.12.96, 6.13.0 to before 6.18.39, and 6.19.0 to before 7.1.4. Fixed in 6.6.145, 6.12.96, 6.18.39, and 7.1.4.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Fix
- Fixed in 6.6.145, 6.12.96, 6.18.39, 7.1.4
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The Linux kernel's ksmbd, the in-kernel SMB server, is affected. When a file marked for delete-on-close was torn down through deferred or durable handle cleanup, the deletion could run with the server's own privileges and skip the file permission checks that apply to the user who opened it, potentially allowing unauthorized file or stream removal.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for delete-on-close Delete-on-close can be completed by deferred or durable handle teardown, where no request work is available. Both the base-file unlink and the ADS xattr removal consequently run with the ksmbd worker credentials and can bypass filesystem permission checks. Run both operations with the credentials captured in struct file when the handle was opened. This preserves the authenticated user's fsuid, fsgid, supplementary groups and capability restrictions at final close.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
5.15
- KernelLinux
From 5.15.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.96; From 6.13.0 · fixed in 6.18.39; From 6.19.0 · fixed in 7.1.4
References 6
git.kernel.org
Questions about CVE-2026-64392
What does this mean?
When a file is marked for delete-on-close, ksmbd finishes the deletion during deferred or durable handle teardown using its own worker credentials instead of the opener's. This can let the base-file unlink and ADS xattr removal bypass filesystem permission checks.Source: git.kernel.org
Am I affected, and how do I check?
The affected range is the Linux kernel ksmbd code from 5.15.0 before 6.6.145, 6.7.0 before 6.12.96, 6.13.0 before 6.18.39, and 6.19.0 before 7.1.4. Check the running kernel with uname -r and whether the ksmbd module is loaded.Source: git.kernel.org
What should I do about it?
Move to the fixed release for the kernel branch in use: 6.6.145, 6.12.96, 6.18.39, or 7.1.4. The sources reviewed here do not give a workaround.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Why do the sources disagree?
The description says the issue needs an authenticated client, but the vector field lists PR:N, which means no privileges are required. The sources do not resolve which of these is correct.Source: git.kernel.org