Apache Traffic Server Header Truncation Enables Request Smuggling

Apache Traffic Server contains a critical vulnerability (CVE-2026-58155, CVSS 9.3) in how it processes HTTP headers. The flaw causes the server to truncate excessively long header names rather than rejecting them, creating header aliasing conditions that enable HTTP request smuggling and security policy bypass attacks. This affects multiple versions across three major release lines: 8.0.0-8.1.9, 9.0.0-9.2.14, and 10.0.0-10.1.3. Organizations running Apache Traffic Server in reverse proxy or load balancing roles face immediate risk, as attackers can craft malicious requests that bypass authentication, WAF rules, and access controls by exploiting the header truncation behavior.

While this CVE currently has no mapped MITRE ATT&CK techniques, Casky.ai's skill framework can detect the attack patterns underlying this vulnerability by analyzing HTTP traffic for anomalies associated with CWE-444 (improper restriction of rendered UI layers or frames). Practitioners using Casky would identify suspicious request patterns through extended reasoning across 754 mapped security skills, including detection of HTTP request smuggling indicators such as: conflicting Content-Length and Transfer-Encoding headers, malformed or unusually long header names, and discrepancies between what the reverse proxy and origin server process. Casky's Claude-powered analysis would flag policy bypass attempts by correlating header manipulation patterns with downstream authorization failures, allowing security teams to pinpoint exploitation attempts before they reach vulnerable backend systems. Immediate action: upgrade to versions 9.2.15 or 10.1.4.