CVE-2026-58187 in Traffic Server
Summary
by MITRE • 07/29/2026
The Apache Traffic Server multiplexer plugin overruns its chunk-decode buffer on upstream input, enabling denial of service.
This issue affects Apache Traffic Server: from 8.0.0 through 8.1.9, from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3.
Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.
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Analysis
by VulDB Data Team • 07/29/2026
The vulnerability in Apache Traffic Server's multiplexer plugin represents a critical buffer overflow condition that occurs during chunked transfer encoding processing of upstream HTTP responses. This flaw exists within the plugin responsible for handling HTTP request and response multiplexing operations, where the system fails to properly validate input data lengths when decoding chunked responses from origin servers. The issue manifests as an insufficient bounds checking mechanism in the chunk-decode buffer implementation, allowing maliciously crafted upstream responses to trigger memory corruption through excessive data writing beyond allocated buffer boundaries.
The technical execution of this vulnerability leverages HTTP chunked transfer encoding, a standard method for transferring data in chunks between HTTP clients and servers. When Apache Traffic Server processes upstream responses containing specially crafted chunked data, the multiplexer plugin attempts to decode these chunks without adequate boundary validation. This creates an exploitable condition where an attacker can send malformed chunked responses that cause the buffer to overflow, potentially leading to memory corruption that may result in application instability or complete service disruption. The vulnerability specifically targets versions within the 8.x, 9.x, and 10.x release series, indicating a long-standing issue affecting multiple major versions of the software.
The operational impact of this vulnerability extends beyond simple denial of service, as it can potentially enable more sophisticated attack vectors depending on the system configuration. While the primary effect is service disruption through resource exhaustion or application crashes, the buffer overflow condition creates opportunities for memory corruption that could theoretically be exploited for privilege escalation or code execution in certain environments. The vulnerability affects the core multiplexer functionality that handles concurrent connections and request processing, making it particularly dangerous in high-traffic environments where the server processes numerous upstream responses simultaneously. Organizations relying on Apache Traffic Server for content delivery, caching, or load balancing operations face significant risk of service interruption when this vulnerability is exploited.
Mitigation strategies should prioritize immediate upgrade to patched versions 9.2.15 or 10.1.4, which contain proper buffer boundary checks and input validation mechanisms. Network-level protections such as rate limiting and upstream response filtering can provide additional defense-in-depth measures while awaiting patch deployment. System administrators should also implement monitoring for unusual patterns in chunked response processing and consider disabling the multiplexer plugin if it is not essential to their operations. This vulnerability aligns with CWE-121, heap-based buffer overflow, and maps to ATT&CK technique T1499.004 for network denial of service attacks, highlighting both the memory corruption nature and the service disruption impact that organizations must address through proper patch management and operational security controls.