{"id":"CVE-2026-63466","aliases":["GHSA-w4mq-xh27-6xpx"],"url":"https://o3.security/vulnerability/CVE-2026-63466","summary":"Unleash: Global Mustache.escape override disables HTML escaping process-wide, enabling Slack/Teams link-injection via unrestricted username","details":"Unleash is an open-source feature management platform. Prior to 8.0.3, FeatureEventFormatterMd.format in src/lib/addons/feature-event-formatter-md.ts assigns Mustache.escape to an identity function before rendering action and path templates. Because Mustache.escape is process-wide, the assignment disables escaping for subsequent Mustache.render calls in email-service.ts, webhook.ts, datadog.ts, and new-relic.ts. An editor-level user can place Slack or Microsoft Teams link syntax in an unrestricted username, trigger a feature event, and inject an attacker-labeled link into a trusted outbound notification channel, while other Mustache sinks remain unescaped until restart. This issue is fixed in version 8.0.3.","published":"2026-08-21T18:21:46.526Z","modified":"2026-08-23T03:49:31.994480669Z","cvss":{"score":4.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"unleash-server","fixedVersion":"8.0.3"}],"fix":{"url":"https://github.com/Unleash/unleash/commit/002012cfdbedd2e9b7db9dc83b9f549f761db22e","label":"Unleash/unleash@002012c"},"references":[{"type":"WEB","url":"https://github.com/Unleash/unleash/releases/tag/v8.0.3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63466.json"},{"type":"ADVISORY","url":"https://github.com/Unleash/unleash/security/advisories/GHSA-w4mq-xh27-6xpx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63466"},{"type":"FIX","url":"https://github.com/Unleash/unleash/commit/002012cfdbedd2e9b7db9dc83b9f549f761db22e"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-23T03:49:31.994480669Z"}}