CVE-2023-38522 in Traffic Server
Summary
by MITRE • 07/26/2024
Apache Traffic Server accepts characters that are not allowed for HTTP field names and forwards malformed requests to origin servers. This can be utilized for request smuggling and may also lead cache poisoning if the origin servers are vulnerable.
This issue affects Apache Traffic Server: from 8.0.0 through 8.1.10, from 9.0.0 through 9.2.4.
Users are recommended to upgrade to version 8.1.11 or 9.2.5, which fixes the issue.
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Analysis
by VulDB Data Team • 09/28/2024
Apache Traffic Server vulnerability CVE-2023-38522 represents a critical HTTP protocol implementation flaw that enables malicious actors to exploit improper validation of HTTP field names within the proxy caching system. This vulnerability stems from the software's acceptance of characters that violate RFC 7230 standards for HTTP field names, which explicitly define valid token characters for header field names. The flaw allows attackers to inject malformed HTTP requests containing invalid field name characters that are subsequently forwarded to origin servers without proper sanitization, creating a pathway for sophisticated attack vectors.
The technical implementation of this vulnerability resides in the HTTP parser component of Apache Traffic Server where field name validation occurs. When processing incoming HTTP requests, the system accepts field names containing characters such as control characters, whitespace, or other invalid tokens that should be rejected according to HTTP specifications. This permissive parsing behavior creates a dangerous condition where maliciously crafted requests can bypass normal validation mechanisms and propagate through the caching infrastructure to backend servers. The vulnerability specifically affects versions from 8.0.0 through 8.1.10 and 9.0.0 through 9.2.4, indicating a widespread impact across multiple release lines of the software.
The operational impact of CVE-2023-38522 extends beyond simple protocol violations to enable serious attack scenarios including HTTP request smuggling and cache poisoning. Request smuggling attacks exploit the inconsistency between how the proxy server and origin server parse malformed requests, potentially allowing attackers to manipulate request boundaries and bypass security controls. The cache poisoning aspect arises when the malformed requests reach vulnerable origin servers, where they may be processed and cached in unexpected ways, leading to corrupted cache content that could be served to legitimate users. This vulnerability directly maps to CWE-20: Improper Input Validation and aligns with ATT&CK technique T1190: Exploit Public-Facing Application, as it represents a weakness in the application's handling of externally received data.
Organizations utilizing Apache Traffic Server in production environments face significant risk from this vulnerability, particularly those with complex caching infrastructures or those serving sensitive content. The attack surface expands when considering that many web applications rely on proper HTTP field validation for security boundaries, making this vulnerability particularly dangerous in multi-tier architectures. The fix implemented in versions 8.1.11 and 9.2.5 addresses the core parsing issue by enforcing stricter validation of HTTP field names according to RFC 7230 specifications. Security teams should prioritize immediate upgrade of affected systems, implement network monitoring for unusual HTTP request patterns, and conduct thorough testing of the patched versions to ensure proper functionality while maintaining security posture.