{"id":"EUVD-2026-20967","revision":"e7e773edab8342f99c68a0b508e0688a","records":[{"revision":"e7e773edab8342f99c68a0b508e0688a","observedAt":"2026-10-28T05:00:31.201+00:00","statement":{"source":"euvd","id":"EUVD-2026-20967","aliases":["CVE-2026-39972"],"title":"Mercure is a protocol for pushing data updates to web browsers and other HTTP clients in a battery-efficient way. Prior to 0.22.0, a cache key collision vulnerability in TopicSelectorStore allows an attacker to poison the match result cache…","description":"Mercure is a protocol for pushing data updates to web browsers and other HTTP clients in a battery-efficient way. Prior to 0.22.0, a cache key collision vulnerability in TopicSelectorStore allows an attacker to poison the match result cache, potentially causing private updates to be delivered to unauthorized subscribers or blocking delivery to authorized ones. The cache key was constructed by concatenating the topic selector and topic with an underscore separator. Because both topic selectors and topics can contain underscores, two distinct pairs can produce the same key. An attacker who can subscribe to the hub or publish updates with crafted topic names can exploit this to bypass authorization checks on private updates. This vulnerability is fixed in 0.22.0.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N","score":7.1,"severity":null}],"references":["https://github.com/dunglas/mercure/security/advisories/GHSA-hwr4-mq23-wcv5","https://github.com/dunglas/mercure/commit/4964a69be904fd61e35b5f1e691271663b6fdd64"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-20967","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Apr 9, 2026, 4:42:22 PM","dateUpdated":"Apr 9, 2026, 6:59:49 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-20967","identifiers":["EUVD-2026-20967","CVE-2026-39972"]},"retained":false,"historicalAffected":[]}],"coverage":[]}