{"id":"CVE-2026-54906","summary":"concurrent-ruby: ReadWriteLock allows wrong-thread write release and stray read-release counter corruption","details":"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.","aliases":["GHSA-6wx8-w4f5-wwcr"],"modified":"2026-07-08T08:13:45.391010667Z","published":"2026-06-24T15:46:01.116Z","related":["CGA-v5cq-m7j4-g9x9"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-414","CWE-667"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54906.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54906.json"},{"type":"ADVISORY","url":"https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-6wx8-w4f5-wwcr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54906"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/ruby-concurrency/concurrent-ruby","events":[{"introduced":"0"},{"fixed":"4c8fc28ab6bb9bd8258a4c0c2fa6d35ebe77b3cb"}],"database_specific":{"cpe":"cpe:2.3:a:rubyconcurrency:concurrent_ruby:*:*:*:*:*:ruby:*:*","extracted_events":[{"introduced":"0"},{"fixed":"1.3.7"}],"source":["AFFECTED_FIELD","CPE_RANGE"]}}],"versions":["v1.3.6","v1.3.5","edge-v0.7.2","v1.3.4","v1.3.3","v1.3.2","edge-v0.7.1","v1.3.1","v1.3.1.pre","v1.3.0","v1.2.3","v1.2.2","v1.2.1","edge-v0.7.0","v1.2.0","v1.1.9","v1.1.8","v1.1.7","v1.1.6","edge-v0.6.0","v1.1.6.pre1","edge-v0.6.0.pre1","v1.1.5","edge-v0.5.0","v1.1.4","v1.1.3","v1.1.2","v1.1.1","edge-v0.4.1","v1.1.0","edge-v0.4.0","v1.1.0.pre2","edge-v0.4.0.pre2","v1.1.0.pre1","edge-v0.4.0.pre1","v1.0.3","edge-v0.2.3","v1.0.5","edge-v0.3.1","v1.0.4","edge-v0.3.0","v1.0.3.pre3","v1.0.3.pre2","v1.0.3.pre1","v1.0.2","v1.0.1","v1.0.0","v1.0.0.pre5","v0.9.1","v1.0.0.pre4","1.0.0.pre3","1.0.0.pre2","v1.0.0.pre1","v0.9.0","v0.9.0.pre3","v0.9.0.pre2","v0.9.0.pre1","v0.8.0","v0.7.2","v0.7.0.1","v0.7.0","v0.7.0.rc3","v0.7.0.rc2","v0.7.0.rc1","v0.6.1","v0.6.0","v0.6.0.pre.2","v0.6.0.pre.1","v0.4.0","v0.3.2","v0.3.1","v0.3.1.pre.2","v0.3.1.pre.1","v0.3.0","v0.3.0.pre.3","v0.3.0.pre.2","0.3.0.pre.1","v0.2.2","v0.0.2","v0.2.1","v0.2.0","v0.1.1.pre.5","v0.1.1.pre.4","v0.1.1.pre.2","v0.1.0","v0.0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54906.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N"}]}