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VulnerabilityPublished Updated

CVE-2025-71074: Linux kernel · functionfs: fix the open/removal races

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in e5bf5ee266633cb18fff6f98f0b7d59a62819eee : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:07 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in e5bf5ee266633cb18fff6f98f0b7d59a62819eee, 75240e5e51c6e6d67a3039384125fa54259a3926, 585a656283c954337036422afcd9cb70dd4135e7
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Linux kernel to e5bf5ee266633cb18fff6f98f0b7d59a62819eee, 75240e5e51c6e6d67a3039384125fa54259a3926 or 585a656283c954337036422afcd9cb70dd4135e7.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0, < e5bf5ee266633cb18fff6f98f0b7d59a62819eee
Fixed in
  • e5bf5ee266633cb18fff6f98f0b7d59a62819eee
LinuxLinuxAffected
  • ≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0, < 75240e5e51c6e6d67a3039384125fa54259a3926
Fixed in
  • 75240e5e51c6e6d67a3039384125fa54259a3926
LinuxLinuxAffected
  • ≥ ddf8abd2599491cbad959c700b90ba72a5dce8d0, < 585a656283c954337036422afcd9cb70dd4135e7
Fixed in
  • 585a656283c954337036422afcd9cb70dd4135e7
LinuxLinuxAffected
  • =2.6.35
Fixed in–

Description

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.

References

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