{"id":"CVE-2018-12423","details":"In Synapse before 0.31.2, unauthorised users can hijack rooms when there is no m.room.power_levels event in force.","aliases":["GHSA-ch5v-fhg8-7gv9","PYSEC-2026-844"],"modified":"2026-07-08T14:14:24.585927Z","published":"2018-06-14T21:29:00.253Z","references":[{"type":"ADVISORY","url":"https://bugs.debian.org/901549"},{"type":"ADVISORY","url":"https://github.com/matrix-org/matrix-doc/issues/1304"},{"type":"ADVISORY","url":"https://matrix.org/blog/2018/06/14/security-update-synapse-0-31-2/"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/matrix-org/synapse","events":[{"introduced":"0"},{"fixed":"667c6546bdbb50c1b5a88effe02ae12322d0d95b"}],"database_specific":{"cpe":"cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"0.31.2"}],"source":"CPE_RANGE"}}],"versions":["v0.31.1","v0.31.0","v0.31.0-rc1","v0.28.0-rc1","v0.25.0-rc1","v0.23.0-rc2","v0.23.0-rc1","v0.18.5","v0.18.4","v0.18.3","v0.18.2","v0.18.1","v0.18.0","v0.17.3","v0.17.2","v0.17.1","v0.17.0","v0.16.1-r1","v0.16.1","v0.16.0","v0.14.0","v0.13.3","v0.13.2","v0.13.1","v0.12.0","v0.11.1","v0.11.0-r2","v0.11.0-r1","v0.11.0","v0.10.0-r2","v0.10.0-r1","v0.10.0","v0.9.3","v0.9.2-r2","v0.9.2-r1","v0.9.2","v0.9.1","v0.9.0-r5","v0.9.0-r4","v0.9.0-r3","v0.9.0-r2","v0.9.0-r1","v0.9.0","v0.8.1-r4","v0.8.1-r3","v0.8.1-r2","v0.8.1-r1","v0.8.1","v0.8.0","v0.7.1-r4","v0.7.1-r3","v0.7.1-r2","v0.7.1-r1","v0.7.1","v0.7.0f","v0.7.0e","v0.7.0d","v0.7.0c","v0.7.0b","v0.7.0a","v0.7.0","v0.6.1f","v0.6.1e","v0.6.1d","v0.6.1c","v0.6.1b","v0.6.1a","v0.6.1","v0.6.0b","v0.6.0a","v0.6.0","v0.5.4a","v0.5.4","v0.5.3c","v0.5.3b","v0.5.3a","v0.5.3","v0.5.2","v0.5.1","v0.5.0","v0.4.2","v0.4.1","v0.3.4","v0.3.3","v0.3.0","v0.2.2","v0.2.1a","v0.2.1","v0.2.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2018-12423.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}