CVE-2026-44897: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in lepture mistune
CVE-2026-44897 is a cross-site scripting (XSS) vulnerability in the Python Markdown parser Mistune prior to version 3. 2. 1. The issue arises because the HTMLRenderer. heading() method constructs the opening <hN> tag by directly concatenating the id attribute value without sanitization. This allows an attacker to inject arbitrary attributes by including a double-quote character in the id, potentially leading to script execution. The vulnerability has a CVSS score of 6. 1 (medium severity) and is fixed in Mistune version 3. 2. 1.
AI Analysis
Technical Summary
Mistune versions before 3.2.1 contain a CWE-79 improper neutralization of input vulnerability in the HTMLRenderer.heading() function. The function builds the heading tag's id attribute by string concatenation without escaping or sanitizing the input. If the id contains a double-quote character, it can break out of the attribute context and inject additional HTML attributes, such as event handlers, enabling cross-site scripting attacks. This vulnerability is addressed in version 3.2.1 of Mistune.
Potential Impact
Successful exploitation allows an attacker to inject arbitrary HTML attributes into heading elements, potentially enabling cross-site scripting attacks that can lead to limited confidentiality and integrity impacts in affected applications using vulnerable Mistune versions. There is no impact on availability. No known exploits are reported in the wild at this time.
Mitigation Recommendations
Upgrade Mistune to version 3.2.1 or later, where this vulnerability is fixed. Since no official patch links or vendor advisory are provided, users should verify the version upgrade from the official Mistune repository or package sources. Patch status is not yet confirmed via vendor advisory; check the vendor's official channels for the latest remediation guidance.
CVE-2026-44897: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in lepture mistune
Description
CVE-2026-44897 is a cross-site scripting (XSS) vulnerability in the Python Markdown parser Mistune prior to version 3. 2. 1. The issue arises because the HTMLRenderer. heading() method constructs the opening <hN> tag by directly concatenating the id attribute value without sanitization. This allows an attacker to inject arbitrary attributes by including a double-quote character in the id, potentially leading to script execution. The vulnerability has a CVSS score of 6. 1 (medium severity) and is fixed in Mistune version 3. 2. 1.
CVSS v3.1
Score 6.1medium
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Mistune versions before 3.2.1 contain a CWE-79 improper neutralization of input vulnerability in the HTMLRenderer.heading() function. The function builds the heading tag's id attribute by string concatenation without escaping or sanitizing the input. If the id contains a double-quote character, it can break out of the attribute context and inject additional HTML attributes, such as event handlers, enabling cross-site scripting attacks. This vulnerability is addressed in version 3.2.1 of Mistune.
Potential Impact
Successful exploitation allows an attacker to inject arbitrary HTML attributes into heading elements, potentially enabling cross-site scripting attacks that can lead to limited confidentiality and integrity impacts in affected applications using vulnerable Mistune versions. There is no impact on availability. No known exploits are reported in the wild at this time.
Mitigation Recommendations
Upgrade Mistune to version 3.2.1 or later, where this vulnerability is fixed. Since no official patch links or vendor advisory are provided, users should verify the version upgrade from the official Mistune repository or package sources. Patch status is not yet confirmed via vendor advisory; check the vendor's official channels for the latest remediation guidance.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-07T21:50:33.546Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a174b8ce29bf47b50e4a24b
Added to database: 5/27/2026, 7:52:44 PM
Last enriched: 5/27/2026, 7:53:12 PM
Last updated: 5/27/2026, 7:53:18 PM
Views: 1
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