CVE-2026-103388 MISP Stored Cross-Site Scripting via JavaScript URL in Galaxy Cluster Source Field
An attacker with galaxy editor privileges can inject JavaScript into cluster source fields, leading to session hijacking or data exfiltration when victims click the link.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-103388?
CVE-2026-103388 is a medium-severity cross-site scripting vulnerability in MISP, published on 30 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-103388?
How do I fix CVE-2026-103388?
No fix has been published for CVE-2026-103388 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-103388 being exploited?
There is no known exploitation of CVE-2026-103388 in the wild and no public exploit code.
Sources
Also known as GHSA-ccjm-jpcq-p5hf.