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CVE-2026-71488
Published:August 06, 2026
Updated:August 31, 2026
league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 0.6.0 until 2.9.0, specially crafted Markdown lines can cause the parser to have quadratic time complexity when converting, because several parsing paths repeatedly rescan growing portions of a line to translate between character positions and byte positions, and the Autolink extension can also copy and validate the remaining line at every URL-like prefix, allowing an attacker who can submit Markdown for conversion to consume disproportionate CPU time with a comparatively small request. This issue is fixed in 2.9.0.
Affected Packages
https://github.com/thephpleague/commonmark.git (GITHUB):
Affected version(s) >=0.6.0 <2.9.0
Fix Suggestion:
Update to version 2.9.0
league/commonmark (PHP):
Affected version(s) >=0.6.0 <2.9.0
Fix Suggestion:
Update to version 2.9.0
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CVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Inefficient Algorithmic Complexity
Excessive Platform Resource Consumption within a Loop
EPSS
Base Score:
0.35