Riskcovery

CVE-2025-40210

Revert "NFSD: Remove the cap on number of operations per NFSv4 COMPOUND"

State
Published
Severity
7.5 High
Published
Nov 21, 2025
Updated
Aug 5, 2026
Reserved
Apr 16, 2025

Read the record on cve.org

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.

Scores

CVSSScoreVectorSource
3.17.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HLinux

Weaknesses

The record names no weakness.

Affected Products

ProductVersions
LinuxLinux
  • 48aab1606fa80027143a445224f552b4eeea845b to before b3ee7ce432289deac87b9d14e01f2fe6958f7f0bAffected
  • 48aab1606fa80027143a445224f552b4eeea845b to before 3e7f011c255582d7c914133785bbba1990441713Affected
LinuxLinux
  • 6.17Affected
  • before 6.17Not affected
  • 6.17.8 through 6.17.*Not affected
  • 6.18 and laterNot affected

References

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