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CVE-2026-117553— Umbraco CMS before 17.7.2 and 18.2.2 Account Takeover via Host Header Poisoning

Quick assessment

Affected
umbraco Umbraco-CMS
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Umbraco CMS 17.7.2 之前版本以及 18.2.2 之前版本中存在一个认证绕过漏洞。该漏洞允许未认证的攻击者通过污染（伪造）Host 头，注册由攻击者控制的 OAuth 重定向 URI。攻击者会向已登录的用户发送授权链接，并设置 以截获授权码，随后利用 HTTP Basic 客户端凭据兑换这些代码，从而劫持后台管理会话，并通过 Razor 模板执行任意代码。

CVSS 7.5 · High
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I. Basic Information for CVE-2026-117553

Vulnerability Information
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Vulnerability Title
Umbraco CMS before 17.7.2 and 18.2.2 Account Takeover via Host Header Poisoning
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
指向未可信站点的URL重定向(开放重定向)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
umbraco Umbraco-CMS 0 ~ 17.7.2 -

II. Public POCs for CVE-2026-117553

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III. Intelligence Information for CVE-2026-117553

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Other References for CVE-2026-117553 (4)

IV. Related Vulnerabilities

Same product: Umbraco-CMS
Same vendor: umbraco
Same weakness: CWE-601