CVE-2026-88921

MEDIUM CVSS 4.0: 5.1 EPSS 0.36%
Updated Sep 10, 2026
Misp
Parameter Value
CVSS 5.1 (MEDIUM)
Type CWE-79 (Cross-Site Scripting (XSS)), CWE-116 (Improper Encoding or Escaping of Output)
Vendor Misp
Public PoC No

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

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
Low
Basic privileges needed
User Interaction
Passive
Minimal interaction

Impact Assessment

Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
None
No disruption

CVSS Vector v4.0

Vulnerable Products

misp:misp