league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. 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
Required
User action required
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products
thephpleague:commonmark
References 3
https://github.com/thephpleague/commonmark/commit/493a5aa7d65754b73846006eaff9c…
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-29pj-957v-5…
security-advisories@github.com