Inefficient regular expression complexity in markdown-it - CVE-2022-21670
Published: January 8, 2022 / Updated: April 24, 2026
Vulnerability identifier: #VU127413
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2022-21670
CWE-ID: CWE-1333
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inefficient regular expression complexity in newline rule when parsing specially crafted markdown input. A remote attacker can send specially crafted input to cause a denial of service.
Inputs containing special patterns with lengths greater than 50,000 characters can significantly slow down the parser.
Affected software
markdown-it
How to mitigate CVE-2022-21670
Install security update from vendor's website.
markdown-it - update to 12.3.2