9.8

CVE-2026-54906: ruby-concurrency concurrent-ruby Missing Lock Check

CVSS: 9.8v3.1CriticalAnalyzed
AliasesUBUNTU-CVE-2026-54906DEBIAN-CVE-2026-54906CGA-334q-rr6r-wppv
Published 24-06-2026Last modified 24-06-2026
Open JSON

Vulnerability summary

CVE-2026-54906 is a critical (CVSS 9.8) Missing Lock Check vulnerability in ruby-concurrency concurrent-ruby. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 15.6% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (NVD)
EPSS score
0.25%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-V5CQ-M7J4-G9X9

Timeline

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

Description

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReadWriteLock#release_write_lock does not verify that the calling thread acquired the write lock. Any thread with access to the lock object can release an active write lock held by another thread. A second writer can then enter its critical section while the first writer is still running. Concurrent::ReadWriteLock#release_read_lock also decrements the shared counter even when no read lock is held. Calling it on a fresh lock changes the counter from 0 to -1, after which normal read acquisition raises Concurrent::ResourceLimitError. This is a synchronization correctness issue in the public Concurrent::ReadWriteLock API. This vulnerability is fixed in 1.3.7.

CVSS metrics

9 scores · 7 sources · 2 versions

EPSS trend

Probability

0.25%

Chance of exploitation in the next 30 days

Percentile

16%

Versus all other CVEs

30-day change

0.00 pp

From 0.25% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.25%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard74 products
  • cinc-auditor< 7.1.7-r7
  • commercial-gitlab-rails-ee-19.1All versions (No fix recorded)
  • commercial-gitlab-rails-ee-19.2< 19.2.7-r4
  • commercial-gitlab-rails-ee-fips-19.1All versions (No fix recorded)
  • commercial-gitlab-rails-ee-fips-19.2< 19.2.7-r4
Wolfi14 products
  • cinc-auditor< 7.1.7-r7
  • kube-fluentd-operator< 1.18.2-r71
  • logstash-9.3All versions (No fix recorded)
  • logstash-9.3-iamguarded-compatAll versions (No fix recorded)
  • logstash-9.4< 9.4.6-r0
Debian1 product
  • ruby-concurrentAll versions (No fix recorded) | < 1.3.7-1
Ruby-concurrency1 product
Rubyconcurrency1 product
RubyGems1 product
  • concurrent-ruby< 1.3.7
Ubuntu1 product
  • ruby-concurrentAll versions (No fix recorded)

7 vendors · 93 products

References

7 links