{"id":"DEBIAN-CVE-2026-54905","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.","modified":"2026-09-01T16:06:51.762307695Z","published":"2026-06-24T17:17:29.403Z","upstream":["CVE-2026-54905"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-54905"}],"affected":[{"package":{"name":"ruby-concurrent","ecosystem":"Debian:12","purl":"pkg:deb/debian/ruby-concurrent?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.6+dfsg-5","1.2.3-1","1.2.3-2","1.2.3-3","1.2.3-4","1.3.4-1","1.3.4-1~exp1","1.3.5-1","1.3.6-1","1.3.7-1","1.3.7-2","1.3.7-3","1.3.7-4","1.3.8-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-54905.json"}},{"package":{"name":"ruby-concurrent","ecosystem":"Debian:13","purl":"pkg:deb/debian/ruby-concurrent?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.5-1","1.3.6-1","1.3.7-1","1.3.7-2","1.3.7-3","1.3.7-4","1.3.8-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-54905.json"}},{"package":{"name":"ruby-concurrent","ecosystem":"Debian:14","purl":"pkg:deb/debian/ruby-concurrent?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.7-1"}]}],"versions":["1.3.5-1","1.3.6-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-54905.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N"}]}