CVE-2021-20270

CVE-2021-20270 is a denial-of-service vulnerability affecting Pygments versions 1.5 to 2.7.3, as well as products like Debian, Fedora, and Red Hat that incorporate these versions. The flaw resides in the SMLLexer component, where an infinite loop can be triggered by specific Standard ML (SML) source code, such as input containing only the "exception" keyword. With a CVSS score of 7.5 (High), this vulnerability can be exploited remotely with low attack complexity, leading to a complete denial of service without requiring user interaction or privileges. Currently, there is no evidence of active exploitation, no public exploit code available (Metasploit, Nuclei, ExploitDB), and minimal community discussion or media coverage.