Bug 2507300 (CVE-2026-64397)

Summary: CVE-2026-64397 kernel: ksmbd: serialize QUERY_DIRECTORY requests per file
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's ksmbd (kernel Server Message Block daemon) component. Concurrent directory query requests using the same file handle can lead to a stack use-after-free vulnerability. This occurs because smb2_query_dir() stores a pointer to stack-allocated data that can be overwritten by another request while still in use. An attacker could exploit this to cause a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-07-25 10:15:17 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ksmbd: serialize QUERY_DIRECTORY requests per file

smb2_query_dir() stores a pointer to its stack-allocated private data in
the ksmbd_file readdir_data. Concurrent QUERY_DIRECTORY requests using the
same file handle can overwrite this pointer while an iterate_dir() callback
is still using it, resulting in a stack use-after-free.

Add a per-file mutex and hold it while accessing the shared directory
enumeration state. The lock covers scan restart, dot entry state,
readdir_data setup and iteration, and response construction. This prevents
another request from replacing readdir_data.private before the current
request has finished using it and also serializes the shared file position.
Comment 1 TEJ RATHI 2026-07-27 05:59:14 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072529-CVE-2026-64397-7e0d@gregkh/T