VulnerabilityAnalyzed

CVE-2026-54906

This vulnerability is fixed in 1.3.7.

LOW 2.1EPSS 0.25%

Does this matter?

Lower severity and a low EPSS score (0.25%). Track it; it rarely justifies an emergency change on its own.

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 4.0: 2.1 LOWCVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.25% probability · 17th percentile
CISA KEV: Not listed
Weakness: CWE-414, CWE-667
Affected: rubyconcurrency/concurrent ruby
Source: security-advisories@github.com

References

https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-6wx8-w4f5-wwcrThird Party Advisory
https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-6wx8-w4f5-wwcrThird Party Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.