CVE-2026-111812: 
Apache Traffic Server vulnerability analysis and mitigation

CVE-2026-111812 is an Incorrect Authorization vulnerability in Apache Traffic Server's origin_server_auth plugin that allows an unauthenticated remote client to force the proxy to sign attacker-chosen AWS request headers using the proxy's own AWS credentials. It affects Apache Traffic Server versions 8.0.0 through 8.1.11, 9.0.0 through 9.2.15, 10.0.0 through 10.1.4, and 10.2.0. The vulnerability was published on October 21, 2026, with patches available the same day. It carries a CVSS v3.1 base score of 10.0 (Critical) and a CVSS v4.0 base score of 7.0 (High) (GitHub Advisory, Apache Mailing List).

The root cause is classified as CWE-863 (Incorrect Authorization): the origin_server_auth plugin fails to properly validate or restrict which AWS request headers a client can submit for signing, allowing any client to supply arbitrary headers that the plugin will then sign using the proxy's own AWS credentials. The attack vector is network-based, requires no privileges or user interaction, and the primary attack requirement is that the origin_server_auth plugin must be enabled and reachable. An attacker crafts HTTP requests to the Traffic Server proxy with attacker-controlled AWS headers, which the plugin signs on their behalf, effectively delegating the proxy's AWS identity to the attacker (GitHub Advisory, Apache Mailing List).

Successful exploitation allows an unauthenticated attacker to forge authenticated AWS API requests using the proxy's own AWS credentials, resulting in high confidentiality and integrity impact on downstream (subsequent) systems — such as AWS services and resources accessible under the proxy's IAM identity. This could enable unauthorized data access, resource manipulation, privilege escalation within AWS environments, and potential lateral movement across cloud infrastructure. The vulnerable system itself (the proxy) has no direct confidentiality or availability impact, but the downstream blast radius is significant depending on the permissions granted to the proxy's AWS credentials (GitHub Advisory).

As of the disclosure date, there is no public proof-of-concept exploit and no evidence of in-the-wild exploitation (GitHub Advisory). The EPSS score is 0.0, indicating a currently low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. No threat actor attribution has been reported at this time.

1. Reconnaissance: Identify internet-facing Apache Traffic Server instances with the origin_server_auth plugin enabled, using network scanning tools (e.g., Shodan, Censys) or by probing known proxy endpoints.
2. Craft malicious request: Construct an HTTP request destined for the Traffic Server proxy that includes attacker-chosen AWS request headers (e.g., custom X-Amz-* headers or manipulated Authorization header fields) targeting the plugin's signing endpoint.
3. Submit request to proxy: Send the crafted request to the vulnerable Traffic Server proxy without any authentication, as no privileges are required.
4. Receive signed headers: The origin_server_auth plugin incorrectly signs the attacker-supplied headers using the proxy's own AWS credentials and forwards or returns the signed request.
5. Forge AWS API calls: Use the proxy-signed headers to make authenticated AWS API requests on behalf of the proxy's IAM identity, gaining access to AWS resources and services permitted under the proxy's permissions (GitHub Advisory, Apache Mailing List).

• Network: Unusual or unexpected HTTP requests to the Apache Traffic Server proxy containing crafted X-Amz-* or AWS Authorization headers from untrusted or external source IPs; outbound AWS API calls from the proxy to unexpected AWS service endpoints.
• Logs: Apache Traffic Server access logs showing requests to the origin_server_auth plugin endpoint with anomalous or externally-supplied AWS header values; AWS CloudTrail logs recording API calls made under the proxy's IAM role from unexpected source IPs or at unusual times.
• AWS CloudTrail: API actions attributed to the proxy's IAM role that do not correspond to legitimate proxy operations, especially from IPs not associated with the proxy infrastructure.

Users should upgrade Apache Traffic Server to version 9.2.16, 10.1.5, or 10.2.1, which contain fixes for this vulnerability. The 8.x branch does not appear to have a patched release listed; users on 8.x should consider migrating to a supported branch. As an interim workaround, disable or restrict access to the origin_server_auth plugin until patching is complete, and implement network-level controls to limit which clients can send requests to the Traffic Server proxy (GitHub Advisory, Apache Mailing List).

The vulnerability was noted on security aggregation platforms and social media shortly after disclosure, including posts on Bluesky and coverage on SecurityOnline.info. No significant vendor statements beyond the Apache advisory or notable independent researcher commentary have been identified at this time (Apache Mailing List).