Umbraco CMS (< 18.2.2) - CraftedSignal Threat Feedhttps://feed.craftedsignal.io/products/umbraco-cms--18.2.2/Trending threats, MITRE ATT&CK coverage, and detection metadata. Fed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioTue, 27 Oct 2026 15:49:43 +0000https://feed.craftedsignal.io/favicon-32x32.pngCraftedSignal Threat Feedhttps://feed.craftedsignal.io/3232https://feed.craftedsignal.io/favicon.svgUmbraco CMS: Authentication bypass (CVE-2026-117553)https://feed.craftedsignal.io/briefs/2026-10-umbraco-auth-bypass/Tue, 27 Oct 2026 15:49:43 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-10-umbraco-auth-bypass/Umbraco CMS contains an authentication bypass vulnerability involving Host header poisoning that allows unauthenticated attackers to hijack back-office sessions and execute code via Razor templates.<p>Umbraco CMS versions before 17.7.2 and 18.2.2 contain an authentication bypass vulnerability. Unauthenticated attackers can poison the Host header to register attacker-controlled OAuth redirect URIs. By sending authorization links using <code>response_mode=form_post</code> to signed-in users, attackers can capture authorization codes. These codes can be redeemed via HTTP Basic client credentials to hijack back-office sessions and execute code through Razor templates.</p> highadvisory