Executive Summary

CVE-2026-12043 is a vulnerability in the AWS Common Runtime aws-c-http library related to improper handling of HPACK dynamic table size updates in HTTP/2. A remote threat actor operating a server can send specially crafted HTTP/2 HEADERS frames that cause memory corruption on a connecting client application.

This memory corruption can potentially lead to arbitrary code execution on the client side.

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Impact Analysis

If you use the affected versions of the aws-c-http library (versions 0.4.22 through 0.10.15) or AWS SDKs that include these versions, a remote server you connect to could exploit this vulnerability by sending crafted HTTP/2 HEADERS frames.

This exploitation could cause memory corruption in your client application, potentially allowing the attacker to execute arbitrary code on your system.

This could lead to unauthorized actions, data compromise, or system instability.

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Detection Guidance

This vulnerability involves improper handling of HPACK dynamic table size updates in HTTP/2 HEADERS frames within the aws-c-http library. Detection would involve identifying usage of vulnerable aws-c-http versions (0.4.22 through 0.10.15) or affected AWS SDK versions in your environment.

You can check the version of the aws-c-http library or AWS SDKs in use on your system or within your applications to detect if they are vulnerable.

• On Linux systems, use commands like `ldd` on your application binaries to identify linked aws-c-http library versions.
• For AWS SDKs, check the version numbers in your project dependencies or package managers (e.g., `mvn dependency:list` for Java, or inspecting package.json or build files).
• Monitor network traffic for suspicious or crafted HTTP/2 HEADERS frames from remote servers, which might require specialized HTTP/2 inspection tools or network analyzers.

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Mitigation Strategies

The primary mitigation is to upgrade the aws-c-http library to version 0.11.0 or later, which contains the fix for this vulnerability.

If upgrading immediately is not possible, a temporary workaround is to force HTTP/1.1 connections instead of HTTP/2, if your environment and applications support it.

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Compliance Impact

CVE-2026-12043 is a high severity vulnerability that can lead to arbitrary code execution, impacting the confidentiality, integrity, and availability of affected systems.

Such impacts could potentially affect compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and system integrity.

However, the provided information does not explicitly describe how this vulnerability directly affects compliance with these standards or regulations.

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