Vulnerability Description
concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReentrantReadWriteLock can incorrectly grant a write lock after one thread acquires the read lock 32,768 times. The lock stores a thread's local read and write hold counts in one integer. The low 15 bits are used for the read hold count, and bit 15 is used as WRITE_LOCK_HELD. After 32,768 reentrant read acquisitions, the local read count crosses into the write-lock bit. try_write_lock then treats the thread as already holding a write lock and returns true without setting the global RUNNING_WRITER bit. This breaks the core mutual-exclusion guarantee: the caller is told it has a write lock, but other threads can still hold or acquire read locks at the same time. This vulnerability is fixed in 1.3.7.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Rubyconcurrency | Concurrent Ruby | < 1.3.7 |
Related Weaknesses (CWE)
References
- https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-wv3Third Party Advisory
- https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-wv3Third Party Advisory
FAQ
What is CVE-2026-54905?
CVE-2026-54905 is a vulnerability with a CVSS score of 5.5 (MEDIUM). concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReentrantReadWriteLock can incorrectly grant a write lock after one thread acquires the read lock 32,768 times. The ...
How severe is CVE-2026-54905?
CVE-2026-54905 has been rated MEDIUM with a CVSS base score of 5.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-54905?
Check the references section above for vendor advisories and patch information. Affected products include: Rubyconcurrency Concurrent Ruby.