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.

Project Subscriptions

Vendors Products
Linux Kernel Subscribe
Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8029-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8030-1 Linux kernel (GCP) vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 25 Nov 2025 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-770
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate


Fri, 21 Nov 2025 10:30:00 +0000

Type Values Removed Values 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.
Title Revert "NFSD: Remove the cap on number of operations per NFSv4 COMPOUND"
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-01-02T15:33:09.752Z

Reserved: 2025-04-16T07:20:57.179Z

Link: CVE-2025-40210

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-11-21T11:15:49.110

Modified: 2025-11-21T15:13:13.800

Link: CVE-2025-40210

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-11-21T00:00:00Z

Links: CVE-2025-40210 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses