Overview
The vulnerability CVE-2024-47252 affects Apache HTTP Server 2.4.63 and earlier versions. An untrusted SSL/TLS client can exploit this weakness to insert escape characters into log files in certain configurations. This can potentially lead to a system compromise or data leakage, making it a critical issue for administrators and security personnel managing Apache HTTP Server environments.
Vulnerability Summary
CVE ID: CVE-2024-47252
Severity: High (7.5 CVSS)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage
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Product | Affected Versions
Apache HTTP Server | 2.4.63 and earlier
How the Exploit Works
The vulnerability is due to insufficient escaping of user-supplied data in mod_ssl. In a logging configuration where CustomLog is used with “%{varname}x” or “%{varname}c” to log variables provided by mod_ssl such as SSL_TLS_SNI, no escaping is performed by either mod_log_config or mod_ssl. This allows an untrusted SSL/TLS client to insert escape characters into log files, leading to unsanitized data appearing in the log files.
Conceptual Example Code
This is a theoretical example of how a HTTP request might exploit the vulnerability:
GET / HTTP/1.1
Host: vulnerable.server.com
SSL_TLS_SNI: www.vulnerable.server.com\r\nInjected_Header: Malicious_Content
In the above example, the attacker inserts a carriage return and newline characters in the SSL_TLS_SNI field, followed by a malicious header. This would then be logged as is by the server, potentially leading to various forms of exploits, including log injection attacks.

