{"schemaVersion":3,"id":"CVE-2026-55671","aliases":["GHSA-29jh-8cfq-rr8x","GO-2026-5059","CGA-55hg-7925-4v9p","CGA-rpfr-f5w8-9rfw"],"status":"published","duplicateOf":null,"title":null,"description":"ZITADEL is an open source identity management platform. From 4.0.0-rc.1 through 4.15.1, ZITADEL's HTTP notification channels, OIDC BackChannel Logout, and SAML metadata URL fetches do not consistently validate user-defined URLs against protected denylist handling, allowing server-side requests to loopback, internal IP, link-local, or redirected endpoints through DNS rebinding, redirects, or protocol downgrades. 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