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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.

MISP是MISP组织开源的一个威胁情报共享与分析平台。 MISP 2.5.45及之前版本存在输入验证错误漏洞，该漏洞源于对用户可配置主页路径验证不足，仅检查路径是否以“/”开头，导致协议相对URL（如 //attacker.example）能被存储为主页值并在登录后用于重定向，容易受到URL重定向攻击。

CVSS 5.1 · Medium EPSS 0.26% · P17

Possible ATT&CK Techniques 1 AI

T1205 · Traffic Signaling

Affected Version Matrix 1

VendorProduct Version RangeStatus
MISP MISP ≤ 2.5.45 affected
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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
Vulnerability Title
MISP 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MISP是MISP组织开源的一个威胁情报共享与分析平台。 MISP 2.5.45及之前版本存在输入验证错误漏洞，该漏洞源于对用户可配置主页路径验证不足，仅检查路径是否以“/”开头，导致协议相对URL（如 //attacker.example）能被存储为主页值并在登录后用于重定向，容易受到URL重定向攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

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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Patches & Fixes for CVE-2026-86351 (1)

Same Patch Batch · MISP · 2026-09-07 · 11 CVEs total

CVE-2026-86452 8.7 HIGH MISP Unauthenticated Mail Endpoints Allow Unbounded Storage Consumption and Request Floodi
CVE-2026-86347 7.1 HIGH MISP Missing Authorization on Template File Upload Allows Authenticated Disk Exhaustion
CVE-2026-86408 7.1 HIGH MISP Missing Authorization in Cryptographic Key View Exposes Signing Keys from Protected E
CVE-2026-86419 7.0 HIGH MISP Insufficient Outbound URL Validation Allows SSRF and Credential Disclosure via Feed R
CVE-2026-86342 5.3 MEDIUM MISP Freetext Feed Preview Improper Authorization Exposes Restricted Event and Feed Inform
CVE-2026-86417 5.3 MEDIUM MISP Dashboard Template REST API Exposes Template Owner Email Addresses to Unauthorized Us
CVE-2026-86451 5.3 MEDIUM MISP Event Graph Object Reference Lookup Exposes References from Unauthorized Objects
CVE-2026-86440 5.1 MEDIUM MISP Dashboard Button Widget Allows Stored XSS via Unsafe javascript: and Backslash URLs
CVE-2026-86418 2.3 LOW MISP Dashboard Organisation Picker Exposes Hidden Organisation Metadata to Unauthorized Us
CVE-2026-86441 2.3 LOW MISP Dashboard Organisation Widgets Bypass Organisation-Index Restrictions and Expose Hidd

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-86351

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