7.5

CVE-2025-21795: NFSD: fix hang in nfsd4_shutdown_callback

Modified
AliasesUBUNTU-CVE-2025-21795DEBIAN-CVE-2025-21795
Published 27-02-2025Last modified 15-10-2026

Vulnerability summary

CVE-2025-21795 is a high (CVSS 7.5) vulnerability in linux. EPSS estimates a 0.67% chance of exploitation in the next 30 days, higher than 51.9% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.67%
0%100%
Low · +0.03 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 35 · Related 31
DLA-4102-1DLA-4178-1RHSA-2025:20095RHSA-2025:20518RHSA-2026:0804SUSE-SU-2025:01919-1

Timeline

  1. 27-02-2025
    PublishedVulnerability first disclosed.
  2. 15-10-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: NFSD: fix hang in nfsd4_shutdown_callback If nfs4_client is in courtesy state then there is no point to send the callback. This causes nfsd4_shutdown_callback to hang since cl_cb_inflight is not 0. This hang lasts about 15 minutes until TCP notifies NFSD that the connection was dropped. This patch modifies nfsd4_run_cb_work to skip the RPC call if nfs4_client is in courtesy state.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.67%

Chance of exploitation in the next 30 days

Percentile

52%

Versus all other CVEs

30-day change

Increase +0.03 pp

From 0.64% 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

No weakness data has been published for this record.

Affected systems

Version check

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

Ubuntu125 products
  • linux< 5.15.0-140.150 | < 6.8.0-78.78
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 5.15.0-1084.91 | < 6.8.0-1035.37
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 67ef9e5fd737eab2495f2586df7e9ea30caa1b77, < abed68027ea3ab893ac85cc46a00e2e64a324239 | ≥ 26540b8940a2e21582afa61a6fb8af87310bac72, < efa8a261c575f816c7e79a87aeb3ef8a0bd6b221 | ≥ 66af25799940b26efd41ea6e648f75c41a48a2c2, < 38d345f612503b850c2973e5a879f88e441b34d7 | ≥ 66af25799940b26efd41ea6e648f75c41a48a2c2, < 23ad7797c74cd8f7f90617f1e59a8703e2b43908 | ≥ 66af25799940b26efd41ea6e648f75c41a48a2c2, < cedfbb92cf97a6bff3d25633001d9c44442ee854 | ≥ 66af25799940b26efd41ea6e648f75c41a48a2c2, < e88d2451cd42e025465d6b51fd716a47b0b3800d | ≥ 66af25799940b26efd41ea6e648f75c41a48a2c2, < 036ac2778f7b28885814c6fbc07e156ad1624d03 | ≥ 5.10.220, < 5.10.235 | ≥ 5.15.154, < 5.15.179 | 5.19
  • linux_kernel≥ 5.10.220, < 5.10.235 | ≥ 5.15.154, < 5.15.179 | ≥ 5.19, < 6.1.129 | ≥ 6.2, < 6.6.79 | ≥ 6.7, < 6.12.16 | ≥ 6.13, < 6.13.4 | 6.14:rc1 | 6.14:rc2
Debian1 product
  • linux< 6.1.129-1 | < 6.12.16-1

3 vendors · 128 products

References

41 links
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