CVE-2026-54905

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.

• CWE-128

• https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-wv3x-4vxv-whppThird Party Advisory
• https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-wv3x-4vxv-whppThird Party Advisory

Published

Jun 24, 2026

Last Modified

Jun 26, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2026-5490DriveLock SQL Injection Privilege Escalation Vulnerability. …8.8
• CVE-2026-54900Oj (Optimized JSON) is a JSON parser and Object marshaller p…6.3
• CVE-2026-54901Oj (Optimized JSON) is a JSON parser and Object marshaller p…6.3
• CVE-2026-54902Oj (Optimized JSON) is a JSON parser and Object marshaller p…6.3
• CVE-2026-54903Oj (Optimized JSON) is a JSON parser and Object marshaller p…6.3
• CVE-2026-54904concurrent-ruby is a modern concurrency tools for Ruby. Prio…7.5
• CVE-2026-54906concurrent-ruby is a modern concurrency tools for Ruby. Prio…9.8
• CVE-2026-54908Pion DTLS is a Go implementation of Datagram Transport Layer…6.3
• CVE-2026-54909pion/stun is a Go implementation of STUN. Prior to 3.1.3, XO…5.3
• CVE-2026-5491DriveLock Directory Traversal Information Disclosure Vulnera…7.5
• CVE-2026-54910FileBrowser Quantum is a free, self-hosted, web-based file m…7.7
• CVE-2026-54911UltraJSON is a fast JSON encoder and decoder written in pure…6.5