CVE-2026-54905 (Medium) detected in concurrent-ruby-1.3.6.gem

Nobody has claimed this yet.

## CVE-2026-54905 - Medium Severity Vulnerability
Vulnerable Library - concurrent-ruby-1.3.6.gem

Modern concurrency tools including agents, futures, promises, thread pools, actors, supervisors, and more.
Inspired by Erlang, Clojure, Go, JavaScript, actors, and classic concurrency patterns.

Library home page: https://rubygems.org/gems/concurrent-ruby-1.3.6.gem

Path to dependency file: /Gemfile.lock

Path to vulnerable library: /vendor/cache/concurrent-ruby-1.3.6.gem

Dependency Hierarchy:
- database_cleaner-active_record-2.2.2.gem (Root Library)
- activerecord-8.0.5.gem
- activemodel-8.0.5.gem
- activesupport-8.0.5.gem
- :x: **concurrent-ruby-1.3.6.gem** (Vulnerable Library)

Found in base branch: master

Vulnerability Details

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.

Publish Date: 2026-06-24

URL: CVE-2026-54905

CVSS 3 Score Details (5.3)

Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Local
- Attack Complexity: Low
- Privileges Required: Low
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: Low
- Integrity Impact: Low
- Availability Impact: Low

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Release Date: 2026-06-19

Fix Resolution: https://github.com/ruby-concurrency/concurrent-ruby.git - v1.3.7

***
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Start with /Gemfile.lock and the cached gem at /vendor/cache/concurrent-ruby-1.3.6.gem; trace the ActiveRecord dependency and update concurrent-ruby to the specified 1.3.7 release. Run the repository's test suite and confirm the lockfile and vendored dependency no longer reference 1.3.6.

Written by the indexing model from the issue text.