CVE-2026-103388: XSS

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.

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Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/MISP/MISP/commit/118528767

Frequently Asked Questions

What is CVE-2026-103388? +

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.

How do I check if I'm vulnerable to CVE-2026-103388? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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