teler-waf is a Go HTTP middleware that provides teler IDS functionality to protect against web-based attacks. In teler-waf prior to version v0.2.0 is vulnerable to a bypass attack when a specific case-sensitive hex entities payload with special characters such as CR/LF and horizontal tab is used. This vulnerability allows an attacker to execute arbitrary JavaScript code on the victim's browser and compromise the security of the web application.

An attacker can exploit this vulnerability to bypass common web attack threat rules in teler-waf and launch cross-site scripting (XSS) attacks. The attacker can execute arbitrary JavaScript code on the victim's browser and steal sensitive information, such as login credentials and session tokens, or take control of the victim's browser and perform malicious actions. This issue has been patched in version 0.2.0.