HIGHCVSS v3.1 7.5Vulnerability
CVE-2026-117553
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.
Properties
- Severity
- HIGH
- Nvd fetched at
- 2026-10-27T15:29:09.616245+00:00
- Cvss severity
- HIGH
- Cvss score
- 7.5
- Retrieved at
- 2026-10-27T15:31:26+00:00
- Score
- 7.5
- Cvss version
- 3.1
- Last source
- NVD
- Cve id
- CVE-2026-117553
- Cvss vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- First seen by Signal
- 2026-10-27T15:31:26+00:00
- Vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- Published at
- 2026-10-27T14:16:35.840
- Last modified
- 2026-10-27T14:16:35.840
Related Entities (1)
HAS_WEAKNESS (1)
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