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CVE-2025-40287
exfat: fix improper check of dentry.stream.valid_size
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.

INFO

Published Date :

Dec. 6, 2025, 10:15 p.m.

Last Modified :

Dec. 6, 2025, 10:15 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2025-40287 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
Solution
Apply kernel patch to fix exFAT filesystem infinite loop vulnerability.
  • Apply the provided kernel patch.
  • Update the Linux kernel.
  • Reboot the system to apply changes.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-40287.

URL Resource
https://git.kernel.org/stable/c/204b1b02ee018ba52ad2ece21fe3a8643d66a1b2
https://git.kernel.org/stable/c/6c627bcc1896ba62ec793d0c00da74f3c93ce3ad
https://git.kernel.org/stable/c/82ebecdc74ff555daf70b811d854b1f32a296bea
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-40287 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-40287 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-40287 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-40287 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Dec. 06, 2025

    Action Type Old Value New Value
    Added 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.
    Added Reference https://git.kernel.org/stable/c/204b1b02ee018ba52ad2ece21fe3a8643d66a1b2
    Added Reference https://git.kernel.org/stable/c/6c627bcc1896ba62ec793d0c00da74f3c93ce3ad
    Added Reference https://git.kernel.org/stable/c/82ebecdc74ff555daf70b811d854b1f32a296bea
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
No CVSS metrics available for this vulnerability.