CVE-2026-86351

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    CVE-2026-86351

    Published: 7 Sept 2026Last Modified: 11 Sept 2026

    Summary: MISP User Homepage Validation Allows Authenticated Open Redirect via Protocol-Relative URL

    Details: 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

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86351.json, https://nvd.nist.gov/vuln/detail/CVE-2026-86351, https://github.com/MISP/MISP/commit/bd454f65a, https://github.com/MISP/MISP

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -bd454f65a

    Affected versions

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2026-86351 | CVE-DB