CVE-2025-38692: exfat: add cluster chain loop check for dir

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-04 · updated 2026-10-30
Weakness: CWE-835

Description

In the Linux kernel, the following vulnerability has been resolved: exfat: add cluster chain loop check for dir An infinite loop may occur if the following conditions occur due to file system corruption. (1) Condition for exfat_count_dir_entries() to loop infinitely. - The cluster chain includes a loop. - There is no UNUSED entry in the cluster chain. (2) Condition for exfat_create_upcase_table() to loop infinitely. - The cluster chain of the root directory includes a loop. - There are no UNUSED entry and up-case table entry in the cluster chain of the root directory. (3) Condition for exfat_load_bitmap() to loop infinitely. - The cluster chain of the root directory includes a loop. - There are no UNUSED entry and bitmap entry in the cluster chain of the root directory. (4) Condition for exfat_find_dir_entry() to loop infinitely. - The cluster chain includes a loop. - The unused directory entries were exhausted by some operation. (5) Condition for exfat_check_dir_empty() to loop infinitely. - The cluster chain includes a loop. - The unused directory entries were exhausted by some operation. - All files and sub-directories under the directory are deleted. This commit adds checks to break the above infinite loop.

Affected products

Linux kernel: from 5.7 before 6.6.103; from 6.7 before 6.12.43; from 6.13 before 6.15.11; from 6.16 before 6.16.2 — fixed in 6.6.103, 6.12.43, 6.15.11, 6.16.2
Linux: 5.7 — fixed in 6.17

How to fix

Upgrade to a fixed version: Linux kernel 6.6.103, 6.12.43, 6.15.11, 6.16.2; Linux 6.17. Check the vendor advisory for mitigations.

References

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