CVE Catalog

CVE-2025-71074

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.10%

1th percentile - higher than 1% of all known CVEs

Summary

A race condition between file open and removal in the Linux kernel's functionfs subsystem was found. ffs_epfile_open() could succeed even though the file was already removed, leading to a use-after-free.

Risk Assessment

An attacker could access freed memory via read()/write() on the opened file, potentially causing system crashes or privilege escalation.

Recommendation

Apply the Linux kernel patch that serializes open operations on ffs->mutex and uses atomic_inc_not_zero() for dynamic files.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: functionfs: fix the open/removal races ffs_epfile_open() can race with removal, ending up with file->private_data pointing to freed object. There is a total count of opened files on functionfs (both ep0 and dynamic ones) and when it hits zero, dynamic files get removed. Unfortunately, that removal can happen while another thread is in ffs_epfile_open(), but has not incremented the count yet. In that case open will succeed, leaving us with UAF on any subsequent read() or write(). The root cause is that ffs->opened is misused; atomic_dec_and_test() vs. atomic_add_return() is not a good idea, when object remains visible all along. To untangle that * serialize openers on ffs->mutex (both for ep0 and for dynamic files) * have dynamic ones use atomic_inc_not_zero() and fail if we had zero ->opened; in that case the file we are opening is doomed. * have the inodes of dynamic files marked on removal (from the callback of simple_recursive_removal()) - clear ->i_private there. * have open of dynamic ones verify they hadn't been already removed, along with checking that state is FFS_ACTIVE.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS