CVE-2026-103662: MISP Reflected XSS in Taxonomy Tag Confirmation Forms

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?

0.3%

EPSS score, percentile 27.2 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

5.1 Medium

CVSS v4.0 base score, given by the CNA

What should I do?

The vulnerability is remediated by HTML-encoding the user-supplied tag name value before it is interpolated into the confirmation form description text. 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 HTML-encoding the user-supplied tag name value before it is interpolated into the confirmation form description text. This ensures that any HTML metacharacters in the input are rendered as inert text rather than executable markup, neutralizing the reflected XSS vector.

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 reflected cross-site scripting (XSS) vulnerability in the legacy taxonomy tag management confirmation forms (add tag and disable tag). The affected forms echoed a user-supplied tag name value from the request unescaped into the rendered HTML output. An attacker who can induce a site administrator to visit a crafted URL containing a malicious tag name parameter can execute arbitra…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-103662 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 1 Oct 2026.
• The CVE record carries a CVSS v4.0 base score of 5.1 (Medium), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.3% (percentile 27.2), 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 Reflected XSS in Taxonomy Tag Confirmation Forms

MISP contains a reflected cross-site scripting (XSS) vulnerability in the legacy taxonomy tag management confirmation forms (add tag and disable tag). The affected forms echoed a user-supplied tag name value from the request unescaped into the rendered HTML output. An attacker who can induce a site administrator to visit a crafted URL containing a malicious tag name parameter can execute arbitrary JavaScript in the administrator's browser session. Preconditions: - The target must be running a MISP instance with the legacy taxonomy tag confirmation views enabled. - The victim must be an authenticated site administrator. - The victim must navigate to the attacker-crafted URL (e.g., via a phishing link). Security impact: - Execution of arbitrary client-side script in the context of the administrator's browser. - Potential theft of session tokens, CSRF tokens, or other sensitive data accessible from the page. - Potential for performing privileged actions on behalf of the administrator within the MISP interface. Affected versions: <2.5.48.

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

Timeline