CVE-2026-86351

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

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/MISP/MISP/commit/bd454f65a	Patch

Configurations

Configuration 1 (hide)

cpe:2.3:a:misp-project:misp:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-09-07 11:17

Updated : 2026-09-09 15:26

NVD link : CVE-2026-86351

Mitre link : CVE-2026-86351

CVE.ORG link : CVE-2026-86351

JSON object : View

Products Affected

misp-project

misp

CWE

CWE-20

Improper Input Validation

CWE-601

URL Redirection to Untrusted Site ('Open Redirect')

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