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CVE-2026-86351— MISP User Homepage Validation Allows Authenticated Open Redirect via Protocol-Relative URL

Quick assessment

Affected
MISP MISP
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.

受影响的 MISP 版本通过检查用户可配置主页的路径是否以 开头来进行验证。该检查不够充分，因为诸如 这样的协议相对 URL 也以 开头，但在浏览器中会解析到外部来源（origin）。 存在漏洞的主页值可存储为用户设置，并在登录后的路由逻辑中被使用。该提交明确指出， 是一个通过验证并在登录后被写入 响应头的攻击载荷。 修复方案引入了一个共享的 ，用于拒绝包含主机名、协议（scheme）、用户信息（userinfo）、以 或 开头的 URL、格式错误的 URL 以及控制字符。此外，该修复还在读取主页设置时重新进行验证

CVSS 5.1 · Medium
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I. Basic Information for CVE-2026-86351

Vulnerability Information
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Vulnerability Title
MISP User Homepage Validation Allows Authenticated Open Redirect via Protocol-Relative URL
Source: CVE Program / CVE List V5
Vulnerability Description
Affected versions of MISP validate the user-configurable homepage by checking only whether the supplied path begins with /. That check is insufficient because protocol-relative URLs such as //attacker.example also begin with / but resolve to an external origin in browsers. The vulnerable homepage value can be stored as a user setting and later used by the post-login routing logic. The commit explicitly identifies //attacker.example as a payload that passed validation and was emitted to the Location header after login. The fix introduces a shared InternalRedirectValidator that rejects URLs containing a host, scheme, userinfo, unsafe leading // or /\, malformed URLs, and control characters. It also revalidates homepage settings on read so legacy or internally written unsafe values cannot bypass the new storage-time validation. Version affected: ≤2.5.45
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
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
MISP MISP 0 ~ 2.5.45 -

II. Public POCs for CVE-2026-86351

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III. Intelligence Information for CVE-2026-86351

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Other References for CVE-2026-86351 (1)

Same Patch Batch · MISP · 2026-09-07 · 3 CVEs total

CVE-2026-86347 7.1 HIGH MISP Missing Authorization on Template File Upload Allows Authenticated Disk Exhaustion
CVE-2026-86342 5.3 MEDIUM MISP Freetext Feed Preview Improper Authorization Exposes Restricted Event and Feed Inform

IV. Related Vulnerabilities

Same product: MISP
Same vendor: MISP
Same weakness: CWE-601

V. Comments for CVE-2026-86351

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