CVE-2026-103388

MISP Stored Cross-Site Scripting via JavaScript URL in Galaxy Cluster Source Field

Published Sep 30, 2026 CVSS 4.0 · 6.2 Medium EPSS < 1% KEV · Not listed
Description
MISP renders the source field of a Galaxy Cluster as a clickable hyperlink whenever the stored value passes PHP's FILTER_VALIDATE_URL validation. Because FILTER_VALIDATE_URL accepts the javascript: URI scheme, a user with galaxy editor privileges on the local instance or on a synced instance could store a javascript: URL as the cluster source.

When another user views the affected Galaxy Cluster and clicks the rendered link, the embedded script executes in the victim's browser context, enabling session hijacking, data exfiltration, or actions performed on behalf of the victim.

Preconditions:

- Attacker must hold galaxy editor privileges (local or via sync).

- Victim must view the affected cluster and click the malicious link.

Impact:

- Stored cross-site scripting (XSS) in the victim's browser.

- Potential session theft, credential harvesting, or unauthorized actions within the MISP application.

Affected: <2.5.48.

Remediation

Vendor Solution

The fix restricts the rendering of the Galaxy Cluster source field as a hyperlink to only http:// and https:// URLs by adding a regular-expression check (preg_match for ^https?://) in addition to the existing FILTER_VALIDATE_URL validation. This prevents javascript: and other non-HTTP URI schemes from being rendered as clickable links, eliminating the stored XSS vector. The change is applied consistently in both the default theme and the Overmind theme.

Tracking

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Advisories

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History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description MISP renders the source field of a Galaxy Cluster as a clickable hyperlink whenever the stored value passes PHP's FILTER_VALIDATE_URL validation. Because FILTER_VALIDATE_URL accepts the javascript: URI scheme, a user with galaxy editor privileges on the local instance or on a synced instance could store a javascript: URL as the cluster source. When another user views the affected Galaxy Cluster and clicks the rendered link, the embedded script executes in the victim's browser context, enabling session hijacking, data exfiltration, or actions performed on behalf of the victim. Preconditions: - Attacker must hold galaxy editor privileges (local or via sync). - Victim must view the affected cluster and click the malicious link. Impact: - Stored cross-site scripting (XSS) in the victim's browser. - Potential session theft, credential harvesting, or unauthorized actions within the MISP application. Affected: <2.5.48.
Title MISP Stored Cross-Site Scripting via JavaScript URL in Galaxy Cluster Source Field
First Time appeared Misp
Misp misp
Weaknesses CWE-79
CPEs cpe:2.3:a:misp:misp:*:*:*:*:*:*:*:*
Vendors & Products Misp
Misp misp
References
Metrics cvssV4_0

{'score': 6.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
CIRCL
Published
Updated
Sep 30, 2026, 3:28 PM
Reserved
Sep 30, 2026, 2:22 PM
Status
Deferred
Published
Sep 30, 2026, 3:22 PM
Modified
Sep 30, 2026, 4:17 PM