5.5

CVE-2026-31575: mm/userfaultfd: fix hugetlb fault mutex hash calculation

Analyzed
AliasesUBUNTU-CVE-2026-31575DEBIAN-CVE-2026-31575CGA-5ghw-3p32-v5hp
Published 24-04-2026Last modified 14-06-2026

Vulnerability summary

CVE-2026-31575 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.9% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.12%
0%100%
Low · -0.04 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 24 · Related 25
OPENSUSE-SU-2026:10703-1SUSE-SU-2026:22043-1SUSE-SU-2026:22048-1SUSE-SU-2026:22076-1SUSE-SU-2026:22087-1USN-8488-1

Timeline

  1. 24-04-2026
    PublishedVulnerability first disclosed.
  2. 14-06-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: mm/userfaultfd: fix hugetlb fault mutex hash calculation In mfill_atomic_hugetlb(), linear_page_index() is used to calculate the page index for hugetlb_fault_mutex_hash(). However, linear_page_index() returns the index in PAGE_SIZE units, while hugetlb_fault_mutex_hash() expects the index in huge page units. This mismatch means that different addresses within the same huge page can produce different hash values, leading to the use of different mutexes for the same huge page. This can cause races between faulting threads, which can corrupt the reservation map and trigger the BUG_ON in resv_map_release(). Fix this by introducing hugetlb_linear_page_index(), which returns the page index in huge page granularity, and using it in place of linear_page_index().

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.12%

Chance of exploitation in the next 30 days

Percentile

2%

Versus all other CVEs

30-day change

Decrease -0.04 pp

From 0.16% 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: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu131 products
  • linux< 6.8.0-136.136 | All versions (No fix recorded) | < 7.0.0-27.27
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 6.8.0-1061.64 | All versions (No fix recorded) | < 7.0.0-1008.8
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Chainguard10 products
  • linux-aws-6.12< 6.12.85-r0
  • linux-aws-6.18< 6.18.31-r0
  • linux-azure-6.18< 6.18.31-r0
  • linux-gcp-6.12< 6.12.85-r0
  • linux-gcp-6.18< 6.18.31-r0
Linux2 products
  • linux≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3, < 5a525c43baaba0bf3063f86996ca3623b71e4172 | ≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3, < 574501ede47ac439afd67ba9812bc66722d500ba | ≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3, < 08282b1bf74c69fc8ecd25493e7fdb5460f01290 | ≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3, < f4689fc089765d36c026063fb22d23533e883eb6 | ≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3, < 0217c7fb4de4a40cee667eb21901f3204effe5ac | 6.7
  • linux_kernel< 6.12.84 | ≥ 6.13, < 6.18.24 | ≥ 6.19, < 6.19.14 | ≥ 7.0, < 7.0.1
Debian1 product
  • linux< 6.12.85-1 | < 6.19.14-1

4 vendors · 144 products

References

28 links
Show all 28 references