ksmbd: serialize QUERY_DIRECTORY requests per file (CVE-2026-64397) | HOL Guard CVE

Critical · CVSS 9.8CVE-2026-64397

ksmbd: serialize QUERY_DIRECTORY requests per file

Answer in brief

CVE-2026-64397 records a Critical severity (CVSS 9.8) vulnerability in ksmbd: serialize QUERY_DIRECTORY requests per file. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jul 25, 2026Updated Sep 4, 2026Source checked Sep 21, 2026First seen by HOL Aug 5, 2026Material review Sep 4, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.8
Exploitation: Not marked as known exploited
Affected software: 3 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:o:linux:linux_kernel::::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <1426fd79102539bc0ab5c8fced047ad4313b9908 \|\| >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <2a64dbf9c739ddf7a25a066507597bf89f8f73d2 \|\| >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <64dac2d486ec1eb18dc00968b16a230b6b75ec24 \|\| >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <a1d5d31cad593ea5e1b637f2f39c9ef6d09d1199 \|\| >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <fd22b039a5a05bc1d6818e9dcd1001fb432a829d \|\| >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <be6d26bf27499977c746abc163659915082348d8	1426fd79102539bc0ab5c8fced047ad4313b9908, 2a64dbf9c739ddf7a25a066507597bf89f8f73d2, 64dac2d486ec1eb18dc00968b16a230b6b75ec24, a1d5d31cad593ea5e1b637f2f39c9ef6d09d1199, fd22b039a5a05bc1d6818e9dcd1001fb432a829d, be6d26bf27499977c746abc163659915082348d8
Linux/Linuxgeneric	5.15	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 1426fd79102539bc0ab5c8fced047ad4313b9908 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jul 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 5, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.