CVE-2025-21795: linux kernel — Fix

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.

Is your site exposed to CVE-2025-21795?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.10.220 — 5.10.235
linux	linux_kernel	5.15.154 — 5.15.179
linux	linux_kernel	5.19 — 6.1.129
linux	linux_kernel	6.2 — 6.6.79
linux	linux_kernel	6.7 — 6.12.16
linux	linux_kernel	6.13 — 6.13.4
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/036ac2778f7b28885814c6fbc07e156ad1624d03 https://git.kernel.org/stable/c/23ad7797c74cd8f7f90617f1e59a8703e2b43908 https://git.kernel.org/stable/c/38d345f612503b850c2973e5a879f88e441b34d7 https://git.kernel.org/stable/c/abed68027ea3ab893ac85cc46a00e2e64a324239 https://git.kernel.org/stable/c/cedfbb92cf97a6bff3d25633001d9c44442ee854 https://git.kernel.org/stable/c/e88d2451cd42e025465d6b51fd716a47b0b3800d https://git.kernel.org/stable/c/efa8a261c575f816c7e79a87aeb3ef8a0bd6b221

Other References

https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html https://cert-portal.siemens.com/productcert/html/ssa-082556.html https://cert-portal.siemens.com/productcert/html/ssa-265688.html

Frequently Asked Questions

What is CVE-2025-21795? +

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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21795? +

CVE-2025-21795 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-21795? +

CVE-2025-21795 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-21795? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-9588 10.0

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in Iron Mountain Archiving Services Inc. …

CVE-2025-57870 10.0

A SQL Injection vulnerability exists in Esri ArcGIS Server versions 11.3, 11.4 and 11.5 on Windows, Linux and Kubernetes. This …

CVE-2026-48286 10.0

Adobe Campaign Classic (ACC) versions 7.4.3 build 9396 and earlier are affected by an Incorrect Authorization vulnerability that could result …

CVE-2026-13782 10.0

Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the renderer …

CVE-2026-48303 10.0

Adobe Campaign Classic (ACC) versions 7.4.3 build 9394 and earlier are affected by an Incorrect Authorization vulnerability that could result …

CVE-2025-34028 10.0

The Commvault Command Center Innovation Release allows an unauthenticated actor to upload ZIP files that represent install packages that, when …

CVE-2025-21795