CVE-2026-104907: MISP: JavaScript Injection via Remote Tag ID in Event Preview Inline Handler

Severity: medium (CVSS 4.8 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-02 · updated 2026-10-02
Weakness: CWE-79

Description

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 products

MISP: before 2.5.48 — fixed in 2.5.48

How to fix

Upgrade to a fixed version: MISP 2.5.48. Check the vendor advisory for mitigations.

References

https://github.com/MISP/MISP/commit/70ad174dd

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