CVE-2023-26047: teler-waf contains detection rule bypass via entities payload

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-03-03 · updated 2026-06-17
Weakness: CWE-79

Description

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.

Affected products

kitabisa teler-waf: before 0.2.0 — fixed in 0.2.0

How to fix

Upgrade to a fixed version: kitabisa teler-waf 0.2.0. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2023-26047 or the next vulnerability affects your stack