7.5

CVE-2025-21900: NFSv4: Fix a deadlock when recovering state on a sillyrenamed file

Modified
AliasesUBUNTU-CVE-2025-21900DEBIAN-CVE-2025-21900
Published 01-04-2025Last modified 05-08-2026

Vulnerability summary

CVE-2025-21900 is a high (CVSS 7.5) Improper Locking vulnerability in linux. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 29.2% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.36%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 3
USN-7521-1USN-7521-3USN-7521-2

Timeline

  1. 01-04-2025
    PublishedVulnerability first disclosed.
  2. 05-08-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: NFSv4: Fix a deadlock when recovering state on a sillyrenamed file If the file is sillyrenamed, and slated for delete on close, it is possible for a server reboot to triggeer an open reclaim, with can again race with the application call to close(). When that happens, the call to put_nfs_open_context() can trigger a synchronous delegreturn call which deadlocks because it is not marked as privileged. Instead, ensure that the call to nfs4_inode_return_delegation_on_close() catches the delegreturn, and schedules it asynchronously.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

29%

Versus all other CVEs

30-day change

Increase +0.01 pp

From 0.35% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu83 products
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
  • linux-aws-5.13All versions (No fix recorded)
  • linux-aws-5.19All versions (No fix recorded)
Linux2 products
  • linux≥ adb4b42d19aea91826621a8d0bac94cf2c08f8bc, < 4fe4ae6c2e01d028856b73b6328b12b8945df871 | ≥ adb4b42d19aea91826621a8d0bac94cf2c08f8bc, < f41a60bc43e7abbc636fee78bed0d74c31e738b0 | ≥ adb4b42d19aea91826621a8d0bac94cf2c08f8bc, < 8f8df955f078e1a023ee55161935000a67651f38 | 6.11
  • linux_kernel≥ 6.11, < 6.12.18 | ≥ 6.13, < 6.13.6 | 6.14:rc1 | 6.14:rc2 | 6.14:rc3 | 6.14:rc4
Debian1 product
  • linux< 6.12.19-1

3 vendors · 86 products

References

10 links