CVE-2025-40287
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…
Overview
CVE-2025-40287 is a known-severity vulnerability. It was published on December 6, 2025.
Technical 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.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How CyberStrike helps
Reason, not just scan
It reasons through your app's logic the way a human pentester would, so it finds flaws signature scanners miss.
Learn moreVerified findings
Every finding is proven exploitable before you see it, which cuts the false positives that bury real risk.
Learn moreAI-driven DAST and SAST
Probe running apps and read source from one engine, so issues are caught before and after they ship.
Learn moreOpen source
Read exactly how it tests and what it reports. CyberStrike is open source and in early access.
View the repo
Frequently asked questions
What is CVE-2025-40287?
CVE-2025-40287 is a known-severity vulnerability. It was published on December 6, 2025.
How severe is CVE-2025-40287?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2025-40287?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2025-40287?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-40287 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.