CVE-2025-25294: Envoy Gateway Log Injection Vulnerability

In all Envoy Gateway versions prior to 1.2.7 and 1.3.1 a default Envoy Proxy access log configuration is used. This format is vulnerable to log injection attacks.

If the attacker uses a specially crafted user-agent which performs json injection, then he could add and overwrite fields to the access log.

Examples of attacks include:

• Using following string as user agent : HELLO-WORLD", "evil-ip": "1.1.1.1", "x-forwarded-for": "1.1.1.1 would lead to setting of new access log properties and overwrite of existing properties. Existing properties such as the value of the X-Forwarded-For header may have importance for security analysis of access logs, and their overwrite can be used to hide malicious activity.

• Using the following string as user-agent : " which renders an invalid json document. The invalid document may fail to be processed by observability solutions, which would allow attacker to hide malicious activity.