ppkarwasz opened a new issue, #4352: URL: https://github.com/apache/logging-log4j2/issues/4352
## Description An HTTP appender header whose value contains a runtime lookup, such as ```xml <Http name="HTTP" url="https://example.com/logs";> <Property name="X-Tenant" value="$${ctx:tenant}"/> <JsonTemplateLayout/> </Http> ``` is evaluated for every event in `HttpURLConnectionManager.send` and passed to `HttpURLConnection.setRequestProperty`. If the resolved value contains a CR or LF character, the JDK rejects it with an `IllegalArgumentException`, so the whole event is not sent (and is reported as an appender error). Context data such as `${ctx:...}` often comes from request headers, so a single value containing a line break is enough to lose the event. Expected behavior: a header value that cannot be sent should not cost the event. For example, the appender could strip or replace CR/LF characters in evaluated header values, or skip the offending header and report it through the status logger. ## Configuration **Version:** 2.26.1 (and `2.x` at `d631e82`) **Operating system:** any **JDK:** any ## Logs An `IllegalArgumentException` from `sun.net.www.protocol.http.HttpURLConnection.checkMessageHeader` ("Illegal character(s) in message header value"), wrapped in an appender error. ## Reproduction With the configuration above, run `ThreadContext.put("tenant", "a\nb")` and log an event: the event is not sent. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
