7.5

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

Deferred
AliasesUBUNTU-CVE-2025-40210DEBIAN-CVE-2025-40210
Published 21-11-2025Last modified 05-08-2026

Vulnerability summary

CVE-2025-40210 is a high (CVSS 7.5) vulnerability in linux. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 29.6% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.36%
0%100%
Low · +0.02 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 6 · Related 5
RHSA-2026:18134USN-8029-1USN-8029-2USN-8029-3USN-8030-1USN-8048-1

Timeline

  1. 21-11-2025
    PublishedVulnerability first disclosed.
  2. 05-08-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

30%

Versus all other CVEs

30-day change

Increase +0.02 pp

From 0.33% 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.

Ubuntu156 products
  • linuxAll versions (No fix recorded) | < 6.17.0-14.14
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 6.17.0-1007.7
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Debian1 product
  • linux< 6.17.8-1
Linux1 product
  • linux≥ 48aab1606fa80027143a445224f552b4eeea845b, < b3ee7ce432289deac87b9d14e01f2fe6958f7f0b | ≥ 48aab1606fa80027143a445224f552b4eeea845b, < 3e7f011c255582d7c914133785bbba1990441713 | 6.17

3 vendors · 158 products

References

12 links
Show all 12 references