{"cve":"CVE-2026-54905","nvd":{"published":"2026-06-24T17:17:29.403","modified":"2026-10-25T22:10:00.150","status":"Analyzed","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_v4":{"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N","score":2.0},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","score":5.5},"cwes":["CWE-128"],"references":["https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-wv3x-4vxv-whpp","https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-wv3x-4vxv-whpp"],"products":["rubyconcurrency:concurrent_ruby"],"source":"nvd","synced_at":"2026-10-25T23:44:33.281319194+00:00"},"epss":{"cve":"CVE-2026-54905","score":0.00153,"percentile":0.04383,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-wv3x-4vxv-whpp","url":"https://osv.dev/vulnerability/GHSA-wv3x-4vxv-whpp","summary":"Concurrent Ruby: `ReentrantReadWriteLock` read-count overflow grants a write lock without exclusivity","modified":"2026-09-10T03:50:50.897491142Z","packages":[{"ecosystem":"RubyGems","name":"concurrent-ruby","purl":"pkg:gem/concurrent-ruby","ranges":["<1.3.7"],"fixed":["1.3.7"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}