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

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 29 Oct 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.4%

EPSS score, percentile 28.8 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

4.8 Medium

CVSS v4.0 base score, given by the CNA

What should I do?

The vulnerability is remediated by casting the remote tag ID to an integer before embedding it in the inline JavaScript onclick handler. Full textSolution from the CVE record.

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

• before 2.5.48

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 29 Oct 2026. About the data.

What to do

Solution (from the CVE record)

The vulnerability is remediated by casting the remote tag ID to an integer before embedding it in the inline JavaScript onclick handler. This ensures only a numeric value is rendered, eliminating the possibility of breaking out of the JavaScript string context with special characters.

Advisories and patches

• Security patch (Patch)

This summary is based on the CVE record as of 29 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

As listed in the CVE record.

Source: CVE List, as of 29 Oct 2026. About the data.

About this vulnerability

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 (suc…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-104907 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 2 Oct 2026.
• The CVE record carries a CVSS v4.0 base score of 4.8 (Medium), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.4% (percentile 28.8), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
• CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact partial.
• The credits in the CVE record name Anthropic (Claude) as finder.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; CVE List, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026. About the data.

Description

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).

Source: CVE List, as of 29 Oct 2026. About the data.

Timeline