5.5

CVE-2026-31458: mm/damon/sysfs: check contexts->nr before accessing contexts_arr[0]

Analyzed
AliasesUBUNTU-CVE-2026-31458DEBIAN-CVE-2026-31458
Published 22-04-2026Last modified 11-05-2026

Vulnerability summary

CVE-2026-31458 is a medium (CVSS 5.5) NULL Pointer Dereference 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 16 · Related 14
MGASA-2026-0108MGASA-2026-0110USN-8567-1USN-8574-1USN-8574-2USN-8574-3

Timeline

  1. 22-04-2026
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs: check contexts->nr before accessing contexts_arr[0] Multiple sysfs command paths dereference contexts_arr[0] without first verifying that kdamond->contexts->nr == 1. A user can set nr_contexts to 0 via sysfs while DAMON is running, causing NULL pointer dereferences. In more detail, the issue can be triggered by privileged users like below. First, start DAMON and make contexts directory empty (kdamond->contexts->nr == 0). # damo start # cd /sys/kernel/mm/damon/admin/kdamonds/0 # echo 0 > contexts/nr_contexts Then, each of below commands will cause the NULL pointer dereference. # echo update_schemes_stats > state # echo update_schemes_tried_regions > state # echo update_schemes_tried_bytes > state # echo update_schemes_effective_quotas > state # echo update_tuned_intervals > state Guard all commands (except OFF) at the entry point of damon_sysfs_handle_cmd().

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

Affected systems

Version check

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

Ubuntu130 products
  • linux< 6.8.0-136.136 | All versions (No fix recorded)
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 6.8.0-1061.64 | All versions (No fix recorded)
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7, < aba546061341b56e9ffb37e1eb661a3628b6ec12 | ≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7, < 1e8da792672481d603fa7cd0d815577220a3ee27 | ≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7, < 708033c231bd782858f4ddbb46ee874a5a5fbdab | ≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7, < bbe03ad3fb9e714191757ca7b41582f930be7be2 | ≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7, < 1bfe9fb5ed2667fb075682408b776b5273162615 | 5.18
  • linux_kernel≥ 5.18, < 6.6.131 | ≥ 6.7, < 6.12.80 | ≥ 6.13, < 6.18.21 | ≥ 6.19, < 6.19.11 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5
Debian1 product
  • linuxAll versions (No fix recorded) | < 6.12.85-1 | < 6.19.11-1

3 vendors · 133 products

References

24 links
Show all 24 references