CVE-2025-40287

Not scored yetLast modified Oct 15, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

exfat: fix improper check of dentry.stream.valid_size

We found an infinite loop bug in the exFAT file system that can lead to a Denial-of-Service (DoS) condition. When a dentry in an exFAT filesystem is malformed, the following system calls — SYS_openat, SYS_ftruncate, and SYS_pwrite64 — can cause the kernel to hang.

Root cause analysis shows that the size validation code in exfat_find() does not check whether dentry.stream.valid_size is negative. As a result, the system calls mentioned above can succeed and eventually trigger the DoS issue.

This patch adds a check for negative dentry.stream.valid_size to prevent this vulnerability.

Metrics

No CVSS score has been published yet.

Affected software

No affected versions have been published.

Timeline

Published
Dec 6, 2025
Last modified
Oct 15, 2026
NVD status
Deferred

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CVE-2025-40287: Unscored | Vulnix