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Mistune CVE-2017-15612

MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2017-10-19 cve@mitre.org
6.1
CVSS 3.0 · NVD
View

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. Public proof-of-concept exploit code is available. EPSS exploitation probability: 0.12%.

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.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAI

mistune.py in Mistune 0.7.4 allows XSS via an unexpected newline (such as in java\nscript:) or a crafted email address, related to the escape and autolink functions. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

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

pypi mistune fix: 0.8

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. mistune.py in Mistune 0.7.4 allows XSS via an unexpected newline (such as in java\nscript:) or a crafted email address, related to the escape and autolink functions. Affected products include: Mistune Project Mistune.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.1 MEDIUM
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

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

DescriptionCVE.org

mistune.py in Mistune 0.7.4 allows XSS via an unexpected newline (such as in java\nscript:) or a crafted email address, related to the escape and autolink functions.

Threat Intelligence Overview

EPSS Score
0.1%
Top 70% exploitable
Exploit
POC
Public exploit code exists
Data Quality
4 sources
Confidence: Medium

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.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC Yes
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

50
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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

cpe:2.3:a:mistune_project:mistune:0.7.4:*:*:*:*:*:*:*
CVE-2026-49851 HIGH POC
8.7 Jun 24

Uncontrolled CPU consumption in Mistune, a Python Markdown parser, allows remote unauthenticated attackers to cause deni

CVE-2026-59928 HIGH POC
7.5 Jul 08

Denial of service in Mistune (the lepture Python Markdown parser) before 3.3.0 lets remote unauthenticated attackers exh

CVE-2026-59922 HIGH POC
7.5 Jul 08

Denial of service in Mistune, a Python Markdown parser, affects all versions prior to 3.3.0 when the strikethrough, mark

CVE-2026-59925 HIGH POC
7.5 Jul 08

Denial of service in Mistune, a widely used pure-Python Markdown parser, affects all versions prior to 3.3.0 where the d

CVE-2026-59923 MEDIUM POC
6.1 Jul 08

Cross-site scripting in Mistune Python Markdown parser (all versions before 3.3.0) allows attacker-controlled Markdown c

CVE-2026-59929 MEDIUM POC
6.1 Jul 08

Cross-site scripting in Mistune prior to 3.3.0 stems from an incomplete URI scheme blocklist in the `safe_url` filter, p

CVE-2026-59924 MEDIUM POC
5.9 Jul 08

Path traversal in Mistune's Include plugin allows reading arbitrary files from the server filesystem when processing att

CVE-2026-59927 MEDIUM POC
5.3 Jul 08

Unbounded recursion in Mistune's Include directive (all versions prior to 3.3.0) can be triggered by a pair of mutually-

CVE-2026-115347 HIGH
8.7 Oct 22

Quadratic denial of service in Mistune's Markdown parser (parse_link_text) affects versions 3.2.0, 3.2.1 and main prior

CVE-2026-121437 HIGH
8.7 Nov 03

Denial of service in Mistune 3.3.0 through 3.3.3 allows unauthenticated remote attackers to exhaust CPU and stall reques

CVE-2026-59930 MEDIUM POC
4.3 Jul 08

Predictable heading anchor ID generation in Mistune's toc plugin (all versions prior to 3.3.0) enables same-page navigat

CVE-2022-34749 HIGH
7.5 Jul 25

In mistune through 2.0.2, support of inline markup is implemented by using regular expressions that can involve a high a

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