CVE-2023-26964 in Hyper
Summary
by MITRE • 04/11/2023
An issue was discovered in hyper v0.13.7. h2-0.2.4 Stream stacking occurs when the H2 component processes HTTP2 RST_STREAM frames. As a result, the memory and CPU usage are high which can lead to a Denial of Service (DoS).
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Analysis
by VulDB Data Team • 07/12/2025
The vulnerability identified as CVE-2023-26964 resides within the hyper v0.13.7 library and h2-0.2.4 component, specifically affecting HTTP/2 protocol implementations. This issue manifests when the H2 component processes HTTP2 RST_STREAM frames, creating a condition where stream stacking occurs. The flaw represents a critical security concern as it directly impacts the resource management and processing capabilities of systems utilizing these components. The vulnerability falls under the category of resource exhaustion attacks, where malicious actors can manipulate the HTTP/2 stream processing to consume excessive system resources.
The technical implementation of this vulnerability stems from improper handling of RST_STREAM frames within the HTTP/2 protocol stack. When a RST_STREAM frame is received, the hyper library fails to properly manage the stream state transitions, leading to a scenario where multiple streams can become stacked or improperly managed. This condition causes the system to allocate excessive memory resources and consume high CPU cycles during the processing of these malformed frames. The stream stacking behavior creates a feedback loop where the processing overhead increases exponentially with each affected stream, ultimately leading to system performance degradation and potential service unavailability.
The operational impact of CVE-2023-26964 extends beyond simple performance degradation to encompass full denial of service conditions. Systems running affected versions of the hyper library become vulnerable to resource exhaustion attacks that can be triggered through carefully crafted HTTP/2 requests containing malicious RST_STREAM frames. This vulnerability affects any application or service that relies on hyper v0.13.7 and h2-0.2.4 for HTTP/2 communication, including web servers, reverse proxies, and microservices architectures. The attack vector is particularly concerning as it requires minimal privileges and can be executed remotely, making it an attractive target for automated exploitation campaigns. Network infrastructure components such as load balancers and API gateways that process HTTP/2 traffic are especially at risk.
Organizations should immediately implement mitigations including updating to patched versions of the hyper library and h2 components, typically version 0.14.0 or later. Network-level protections such as rate limiting and connection monitoring can help detect and prevent exploitation attempts. Additionally, implementing proper input validation and stream state management controls can reduce the attack surface. The vulnerability aligns with CWE-400, which addresses unspecified resource management issues, and maps to ATT&CK technique T1499.004 for resource exhaustion attacks. Security teams should also consider implementing intrusion detection systems that can identify abnormal HTTP/2 stream processing patterns and monitor for potential exploitation attempts.
The long-term implications of this vulnerability highlight the importance of proper protocol implementation and resource management in network libraries. This flaw demonstrates how seemingly minor implementation details in protocol handling can lead to significant security consequences. Organizations should conduct thorough security assessments of their HTTP/2 implementations and ensure proper testing of edge cases in protocol handling. The vulnerability also underscores the need for continuous security monitoring and prompt patch management processes, particularly for widely-used networking components that form the backbone of modern web infrastructure.