CVE-2026-103389: MISP Stored Cross-Site Scripting via Unvalidated Galaxy Icon Field in Correlation Graph

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 22.9 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 vulnerability is remediated by enforcing strict input validation on the galaxy icon field so that only valid Font Awesome icon names (lowercase alphanumeric … 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 enforcing strict input validation on the galaxy icon field so that only valid Font Awesome icon names (lowercase alphanumeric characters and dashes) are accepted at write time. The sync/import capture path discards any icon value that does not conform. The correlation graph JSON generation falls back to a safe default icon for any previously stored invalid value. On the client side, both correlation graph scripts now set the icon as a CSS class attribute rather than injecting it as raw HTML, and apply an additional regex sanitization pass. The asset cache-busting version is incremented to ensure browsers load the corrected scripts.

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 stored cross-site scripting (XSS) vulnerability in the galaxy icon handling path. The icon field of a galaxy object was persisted without any server-side validation through the galaxy add, edit, and sync/import capture endpoints. The stored value was subsequently concatenated directly into HTML markup by the D3-based correlation graph rendering scripts (both the default and Overmi…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-103389 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 30 Sep 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 0.3% (percentile 22.9), 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 Stored Cross-Site Scripting via Unvalidated Galaxy Icon Field in Correlation Graph

MISP contains a stored cross-site scripting (XSS) vulnerability in the galaxy icon handling path. The icon field of a galaxy object was persisted without any server-side validation through the galaxy add, edit, and sync/import capture endpoints. The stored value was subsequently concatenated directly into HTML markup by the D3-based correlation graph rendering scripts (both the default and Overmind themes) using the .html() method. A user holding the perm_galaxy_editor permission, which is granted to the stock User role, could store arbitrary HTML or JavaScript in the icon field. Any other user who opened the correlation graph of an event containing a cluster belonging to that galaxy would have the injected script executed in their browser session. Impact: - Arbitrary script execution in the context of the victim's MISP session - Potential theft of session credentials, manipulation of displayed data, or initiation of actions on behalf of the victim - Affects both the default and Overmind UI themes Affected versions: <2.5.48

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

Timeline