{"id":"CVE-2026-54906","state":"PUBLISHED","title":"concurrent-ruby: ReadWriteLock allows wrong-thread write release and stray read-release counter corruption","description":"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.","publishedAt":"2026-06-24T15:46:01.116Z","updatedAt":"2026-06-24T17:57:07.650Z","severity":{"score":2.1,"label":"Low","version":"4.0","vector":"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","source":"GitHub_M"},"assigner":"GitHub_M","products":["ruby-concurrency concurrent-ruby"],"affected":[{"vendor":"ruby-concurrency","product":"concurrent-ruby","versions":[{"version":"< 1.3.7","status":"affected"}]}],"references":["https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-6wx8-w4f5-wwcr"],"weaknesses":["CWE-414","CWE-667"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/54xxx/CVE-2026-54906.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54906","state":"PUBLISHED","datePublished":"2026-06-24T15:46:01.116Z","dateUpdated":"2026-06-24T17:57:07.650Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T13:49:33.556Z"},"containers":{"cna":{"title":"concurrent-ruby: ReadWriteLock allows wrong-thread write release and stray read-release counter corruption","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"ruby-concurrency","product":"concurrent-ruby","versions":[{"version":"< 1.3.7","status":"affected"}]}],"references":[{"url":"https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-6wx8-w4f5-wwcr","name":"https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-6wx8-w4f5-wwcr","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV4_0":{"attackVector":"LOCAL","attackComplexity":"HIGH","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":2.1,"baseSeverity":"LOW","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-414","lang":"en","description":"CWE-414: Missing Lock Check","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-667","lang":"en","description":"CWE-667: Improper Locking","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-06-24T15:46:01.116Z"},"source":{"advisory":"GHSA-6wx8-w4f5-wwcr","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-6wx8-w4f5-wwcr","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-24T17:56:44.670673Z","id":"CVE-2026-54906","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-24T17:57:07.650Z"}}]}}}