CVE-2026-5389
Published:August 23, 2026
Updated:September 24, 2026
justhtml versions before 1.13.0 contain a cross-site scripting vulnerability in the to_markdown() function when serializing attacker-controlled pre content. Attackers can place backticks inside sanitized pre elements to break out of fixed-length code fences, allowing raw HTML to execute when the generated Markdown is rendered by CommonMark or GFM-style renderers.
Affected Packages
justhtml (PYTHON):
Affected version(s) >=0.1.0 <1.13.0Fix Suggestion:
Update to version 1.13.0Related Resources (7)
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Contact UsCVSS v4
Base Score:
5.1
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
ACTIVE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
NONE
Subsequent System Confidentiality
LOW
Subsequent System Integrity
LOW
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.1
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
EPSS
Base Score:
0.19