Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| umbraco | Umbraco-CMS | < 17.7.2, 18.0.0 – < 18.2.2 | 17.7.2 |
References
- Patch Commit patch
- https://github.com/umbraco/Umbraco-CMS product
- GitHub Security Advisory (GHSA-rpv9-qp4c-g469) vendor-advisory
- https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.1/src/Umbraco.Cms.Api.Management/Middleware/BackOfficeAuthorizationInitializationMiddleware.cs#L74-L112 technical-description
- VulnCheck Advisory: Umbraco CMS before 17.7.2 and 18.2.2 Account Takeover via Host Header Poisoning third-party-advisory