CVE-2026-117553highCWE-601

CVE-2026-117553: high-severity vulnerability in Umbraco-CMS

Umbraco CMS before 17.7.2 and 18.2.2 Account Takeover via Host Header Poisoning

Published

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21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.7epss 0.5%
Umbraco CMS before 17.7.2 and 18.2.2 contains an authentication bypass vulnerability that allows unauthenticated attackers to register attacker-controlled OAuth redirect URIs by poisoning the Host header. Attackers send signed-in users authorization links using response_mode=form_post to capture codes, then redeem them via HTTP Basic client credentials to hijack back-office sessions and execute code through Razor templates.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Affected products
umbraco · Umbraco-CMS
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