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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Vulnerable Products
thephpleague:commonmark
References 5
https://github.com/thephpleague/commonmark/commit/a6ef6cdc308dfa39a34239c35818e…
security-advisories@github.com
https://github.com/thephpleague/commonmark/commit/a70979ea0d7d3377bd71275367484…
security-advisories@github.com
https://github.com/thephpleague/commonmark/commit/c97b02e5e652b992033b93ba5d618…
security-advisories@github.com
https://github.com/thephpleague/commonmark/releases/tag/2.9.0
security-advisories@github.com
https://github.com/thephpleague/commonmark/security/advisories/GHSA-2q4p-g7hv-5…
security-advisories@github.com