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CVE-2025-40210
Revert "NFSD: Remove the cap on number of operations per NFSv4 COMPOUND"
Description

In the Linux kernel, the following vulnerability has been resolved: Revert "NFSD: Remove the cap on number of operations per NFSv4 COMPOUND" I've found that pynfs COMP6 now leaves the connection or lease in a strange state, which causes CLOSE9 to hang indefinitely. I've dug into it a little, but I haven't been able to root-cause it yet. However, I bisected to commit 48aab1606fa8 ("NFSD: Remove the cap on number of operations per NFSv4 COMPOUND"). Tianshuo Han also reports a potential vulnerability when decoding an NFSv4 COMPOUND. An attacker can place an arbitrarily large op count in the COMPOUND header, which results in: [ 51.410584] nfsd: vmalloc error: size 1209533382144, exceeds total pages, mode:0xdc0(GFP_KERNEL|__GFP_ZERO), nodemask=(null),cpuset=/,mems_allowed=0 when NFSD attempts to allocate the COMPOUND op array. Let's restore the operation-per-COMPOUND limit, but increased to 200 for now.

INFO

Published Date :

Nov. 21, 2025, 11:15 a.m.

Last Modified :

Nov. 21, 2025, 3:13 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2025-40210 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
Solution
Revert a change that removed the operation limit for NFSv4 COMPOUND operations.
  • Apply the patch to revert the change.
  • Re-enable the operation-per-COMPOUND limit.
  • Consider increasing the limit if needed.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-40210.

URL Resource
https://git.kernel.org/stable/c/3e7f011c255582d7c914133785bbba1990441713
https://git.kernel.org/stable/c/b3ee7ce432289deac87b9d14e01f2fe6958f7f0b
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-40210 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-40210 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-40210 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-40210 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Nov. 21, 2025

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved: Revert "NFSD: Remove the cap on number of operations per NFSv4 COMPOUND" I've found that pynfs COMP6 now leaves the connection or lease in a strange state, which causes CLOSE9 to hang indefinitely. I've dug into it a little, but I haven't been able to root-cause it yet. However, I bisected to commit 48aab1606fa8 ("NFSD: Remove the cap on number of operations per NFSv4 COMPOUND"). Tianshuo Han also reports a potential vulnerability when decoding an NFSv4 COMPOUND. An attacker can place an arbitrarily large op count in the COMPOUND header, which results in: [ 51.410584] nfsd: vmalloc error: size 1209533382144, exceeds total pages, mode:0xdc0(GFP_KERNEL|__GFP_ZERO), nodemask=(null),cpuset=/,mems_allowed=0 when NFSD attempts to allocate the COMPOUND op array. Let's restore the operation-per-COMPOUND limit, but increased to 200 for now.
    Added Reference https://git.kernel.org/stable/c/3e7f011c255582d7c914133785bbba1990441713
    Added Reference https://git.kernel.org/stable/c/b3ee7ce432289deac87b9d14e01f2fe6958f7f0b
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
No CVSS metrics available for this vulnerability.