CVE-2026-104907: MISP: JavaScript Injection via Remote Tag ID in Event Preview Inline Handler
MISP contains a cross-site scripting (XSS) vulnerability in the remote event preview page. When a linked (remote) MISP server is configured, the event preview renders tag identifiers inside an inline JavaScript onclick attribute. The tag ID value was HTML-escaped but not sanitized for the JavaScript string context, meaning a malicious linked server could supply a tag ID containing characters (such as a single quote) that break out of the JavaScript string literal and inject arbitrary script.
Preconditions:
- A linked/remote MISP server is configured and connected to the local instance.
- The linked server supplies a crafted tag ID in an event.
- An authenticated user views the event preview and interacts with the affected tag element.
Impact:
- Arbitrary JavaScript execution in the context of the viewing user's browser session, potentially allowing session hijacking, data exfiltration, or unauthorized actions on behalf of the user.
Affected versions: MISP prior to the fix commit (v2.5.48 or later, exact boundary unconfirmed).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
MISPto a version that resolves this vulnerability.Fixed in v2.5.48
Event History
Frequently Asked Questions
Which deployments are exposed?
Exposure requires a local MISP instance to have a linked and connected remote MISP server. The remote server must provide an event with a crafted tag ID, so instances without such a remote link do not meet the stated preconditions.
What user action is required for exploitation?
An authenticated user must open the remote event preview and interact with the affected tag element. The attack executes in that viewing user's browser session.
What can be done if the fix cannot be applied immediately?
Avoid interacting with tag elements in previews of events supplied by linked remote servers. Where practical, disconnect or do not trust remote MISP links that could supply malicious event data until the issue is remediated.
How can I determine whether my version is affected?
The issue is described as affecting MISP before commit 70ad174dd. Although v2.5.48 or later is referenced, the exact fixed-version boundary is unconfirmed, so compare the deployed code or package contents against the fix commit rather than relying solely on a version boundary.