CVE-2026-88921 MISP: Unescaped HTML Injection in PDF Report Element Rendering
Authenticated users can inject HTML into MISP PDF reports, potentially executing scripts or altering document integrity during export.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-88921?
CVE-2026-88921 is a medium-severity cross-site scripting vulnerability in MISP, published on 10 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
MISP contains an HTML injection vulnerability in the MISPElementHTMLFormatterTool component, which is responsible for rendering MISP element references (attributes, objects, and tags) into inline HTML during PDF report export via the convert_markdown_to_pdf module. The attribute(), objectAttribute(), object(), and tag() methods interpolated user-controlled fields (attribute type, attribute value, object name, object relation, tag name, tag colour, and tag text colour) directly into HTML templates without applying HTML entity encoding. An authenticated user with the ability to create or modify MISP attributes, objects, or tags could embed arbitrary HTML markup in these fields. When a report containing such elements was exported to PDF, the unescaped content was rendered as live HTML rather than inert text, potentially injecting script tags, breaking the document structure, or altering the visual content of the exported report. Additionally, the attribute() method contained a template with hardcoded sample values ("domain-ip" and "google.com") instead of format placeholders, meaning every plain attribute reference in a PDF displayed the sample text rather than the actual indicator value, constituting a data-integrity defect in the exported document. The vulnerability requires an authenticated actor with write access to MISP elements and a subsequent PDF export of a report referencing those elements. The security impact is primarily to the integrity of the exported document and, depending on the HTML-to-PDF rendering engine, potential execution of injected markup during the conversion step.
Version affected: ≤2.5.45
Which versions are affected by CVE-2026-88921?
How do I fix CVE-2026-88921?
No fix has been published for CVE-2026-88921 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-88921 being exploited?
There is no known exploitation of CVE-2026-88921 in the wild and no public exploit code.
Sources
Also known as GHSA-6h22-87v4-49wc.