CVE-2026-64397: Linux Kernel

Critical severity, CVSS 9.8. EPSS: 0.7% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux Kernel: from 5.15, before 6.1.178 (fixed in 6.1.178); from 6.2, before 6.6.145 (fixed in 6.6.145); from 6.7, before 6.12.96 (fixed in 6.12.96); from 6.13, before 6.18.39 (fixed in 6.18.39); from 6.19, before 7.1.4 (fixed in 7.1.4)

Published 2026-07-25. Last modified 2026-09-04.