matrix-appservice-irc is a Node.js IRC bridge for Matrix. Prior to version 1.0.1, it is possible to craft a command with newlines which would not be properly parsed. This would mean you could pass a string of commands as a channel name, which would then be run by the IRC bridge bot. Versions 1.0.1 and above are patched. There are no robust workarounds to the bug. One may disable dynamic channels in the config to disable the most common execution method but others may exist.
Conclusion & alert: CVE-2023-38690 is rated Low Risk (36.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.18%).Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
Exploit prediction scoring system (EPSS) score for CVE-2023-38690
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).