CVE-2026-104906: MISP TAXII Object Viewer Stored XSS via Unescaped JSON Output

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 29.7 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

6.2 Medium

CVSS v4.0 base score, given by the CNA

What should I do?

The fix applies HTML-encoding (via the h() helper) to the JSON string before it is interpolated into the HTML pre element. 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 fix applies HTML-encoding (via the h() helper) to the JSON string before it is interpolated into the HTML pre element. This ensures that any HTML or script markup present in the JSON string properties of a TAXII object is rendered as inert text rather than being parsed and executed by the browser, eliminating the 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 cross-site scripting (XSS) vulnerability in the TAXII object viewer. When displaying a remote TAXII object, the JSON content of string properties was rendered directly into an HTML pre block without HTML-encoding. An attacker who can control or influence the content of a TAXII object (e.g., by publishing a malicious object to a TAXII server that the victim's MISP instance subscrib…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-104906 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 6.2 (Medium), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.4% (percentile 29.7), 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 TAXII Object Viewer Stored XSS via Unescaped JSON Output

MISP contains a cross-site scripting (XSS) vulnerability in the TAXII object viewer. When displaying a remote TAXII object, the JSON content of string properties was rendered directly into an HTML pre block without HTML-encoding. An attacker who can control or influence the content of a TAXII object (e.g., by publishing a malicious object to a TAXII server that the victim's MISP instance subscribes to) can inject arbitrary HTML or JavaScript that executes in the context of the victim's MISP session. Preconditions: - The victim must be an authenticated MISP user with access to the TAXII object viewer. - The victim must open or view the crafted TAXII object. Impact: - Execution of arbitrary JavaScript in the victim's browser within the MISP application context. - Potential theft of session tokens, API keys, or other sensitive data accessible from the MISP interface. - Potential for performing actions on behalf of the authenticated user. Affected versions: <2.5.48.

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

Timeline