Mistune
CVE-2017-16876
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK
2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 6.1 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required. EPSS exploitation probability: 0.23%. |
| Exploit ScenarioDerived | A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAI
Cross-site scripting (XSS) vulnerability in the _keyify function in mistune.py in Mistune before 0.8.1 allows remote attackers to inject arbitrary web script or HTML by leveraging failure to escape. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in pypi
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. Cross-site scripting (XSS) vulnerability in the _keyify function in mistune.py in Mistune before 0.8.1 allows remote attackers to inject arbitrary web script or HTML by leveraging failure to escape the "key" argument. Affected products include: Mistune Project Mistune, Fedoraproject Fedora. Version information: before 0.8.1.
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Severity by source
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionCVE.org
Cross-site scripting (XSS) vulnerability in the _keyify function in mistune.py in Mistune before 0.8.1 allows remote attackers to inject arbitrary web script or HTML by leveraging failure to escape the "key" argument.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.
Affected Products (CPE)CVE.org
Uncontrolled CPU consumption in Mistune, a Python Markdown parser, allows remote unauthenticated attackers to cause deni
mistune.py in Mistune 0.7.4 allows XSS via an unexpected newline (such as in java\nscript:) or a crafted email address,
Quadratic denial of service in Mistune's Markdown parser (parse_link_text) affects versions 3.2.0, 3.2.1 and main prior
Denial of service in Mistune (the lepture Python Markdown parser) before 3.3.0 lets remote unauthenticated attackers exh
Denial of service in Mistune, a Python Markdown parser, affects all versions prior to 3.3.0 when the strikethrough, mark
Denial of service in Mistune, a widely used pure-Python Markdown parser, affects all versions prior to 3.3.0 where the d
In mistune through 2.0.2, support of inline markup is implemented by using regular expressions that can involve a high a
Cross-site scripting in Mistune Python Markdown parser (all versions before 3.3.0) allows attacker-controlled Markdown c
Cross-site scripting in Mistune prior to 3.3.0 stems from an incomplete URI scheme blocklist in the `safe_url` filter, p
Path traversal in Mistune's Include plugin allows reading arbitrary files from the server filesystem when processing att
Cross-site scripting in Mistune (Python Markdown parser) prior to version 3.2.1 allows injection of arbitrary HTML attri
Unbounded recursion in Mistune's Include directive (all versions prior to 3.3.0) can be triggered by a pair of mutually-
Exploit-DB