{"id":"EM-20261110-XHM3","url":"https://cyber.eventmonitor.net/incident/EM-20261110-XHM3/active-support-vulnerability-cve-2026-126075/","type":"cve","title":"Active Support Vulnerability (CVE-2026-126075)","subtitle":"CVE-2026-126075","subject":"CVE-2026-126075","status":"Developing","severity":"medium","affected":[],"headline":null,"born":"2026-11-10T21:27:12.000Z","firstSignal":"2026-11-10T20:50:44.000Z","lastSignal":"2026-11-10T21:27:12.000Z","updated":"2026-11-11T12:38:43.721Z","revision":1,"life":[{"status":"Born","at":"2026-11-10T21:27:12.000Z","why":"second independent source: C26 GitHub Advisory Database"},{"status":"Developing","at":"2026-11-10T21:27:12.000Z","why":"signals keep joining"}],"changeLog":[{"at":"2026-11-10T20:50:44.000Z","what":"First signal: C41 Red Hat Security Data"},{"at":"2026-11-10T21:27:12.000Z","what":"Born: second source, C26 GitHub Advisory Database. Page EM-20261110-XHM3 created."}],"stages":[{"name":"Disclosed","at":"2026-11-10T21:19:25.880Z","detail":"C6 NVD published"},{"name":"Scored","at":"2026-11-10T21:19:25.880Z","detail":"CVSS 4.7"},{"name":"Exploited","at":null,"detail":"No exploitation reported"},{"name":"Advisories","at":null,"detail":"None yet"},{"name":"Vendor Response","at":"2026-11-10T20:50:44.000Z","detail":"C41 published"},{"name":"Resolved","at":null,"detail":"After 14 quiet days"}],"signals":[{"at":"2026-11-10T20:50:44.000Z","source":"C41","sourceName":"Red Hat Security Data","role":"Vendor","severity":2,"title":"Red Hat: CVE-2026-126075 (moderate)","text":"activesupport: Active Support: Cross-site scripting via MessagePack deserialization","url":"https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-126075.json"},{"at":"2026-11-10T21:27:12.000Z","source":"C26","sourceName":"GitHub Advisory Database","role":"Database","severity":2,"title":"GHSA-2w9f-fxwj-w2qf / CVE-2026-126075: Active Support: Possible XSS vulnerability in Active Support MessagePack serializer","text":"rubygems:activesupport","url":"https://github.com/advisories/GHSA-2w9f-fxwj-w2qf"}],"crowd":[],"reference":{"nvd":{"published":"2026-11-10T21:19:25.880","score":4.7,"severity":"MEDIUM","desc":"Active Support is a collection of utility classes and standard library extensions used by Rails and other Ruby projects. From 8.1 until 8.1.4.1, ActiveSupport::MessagePack serializes an ActiveSupport::SafeBuffer as its bytes alone and deserializes it as a new SafeBuffer, so a buffer that is no…","product":"","seen":1794353084878},"kev":null,"epss":null,"p0":false},"mergedInto":null,"publisher":"Event Monitor Cyber"}