CVE-2018-6347 in Proxygen
Summary
by MITRE
An issue in the Proxygen handling of HTTP2 parsing of headers/trailers can lead to a denial-of-service attack. This affects Proxygen prior to v2018.12.31.00.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability identified as CVE-2018-6347 represents a critical denial-of-service weakness within Facebook's Proxygen HTTP/2 library implementation. This flaw specifically manifests during the parsing of HTTP/2 headers and trailers, creating a scenario where maliciously crafted HTTP/2 frames can trigger unexpected behavior in the library's processing logic. The issue affects all versions of Proxygen released prior to the December 31, 2018, release cycle, leaving a substantial window of vulnerable software in production environments. The vulnerability stems from inadequate input validation and error handling within the HTTP/2 header processing pipeline, where the library fails to properly sanitize or reject malformed header frames that could cause memory corruption or resource exhaustion.
The technical exploitation of this vulnerability occurs when an attacker sends specially crafted HTTP/2 frames containing malformed headers or trailers to a server running a vulnerable version of Proxygen. The library's HTTP/2 parser lacks proper bounds checking and validation mechanisms that would normally prevent malformed data from causing system instability. When processing these malformed frames, the parser enters an unpredictable state where it may attempt to access invalid memory locations or consume excessive computational resources. This behavior aligns with CWE-129, which addresses improper validation of length values, and CWE-772, concerning missing release of resource after effective lifetime, as the parser fails to properly handle malformed input sequences that should trigger graceful error recovery mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged to create sustained denial-of-service conditions that are difficult to distinguish from legitimate traffic patterns. Attackers can exploit this weakness to consume server resources rapidly, potentially causing application crashes, memory exhaustion, or complete service unavailability. The vulnerability is particularly concerning in high-traffic environments where HTTP/2 is extensively used, as it can be exploited to cause cascading failures across multiple services. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1499.004, which covers network denial of service attacks, and T1071.004, covering application layer protocol usage, making it a significant threat vector in modern web infrastructure.
Mitigation strategies for CVE-2018-6347 primarily focus on immediate software updates to the latest stable version of Proxygen that includes proper header validation and error handling mechanisms. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly. Network-level protections such as rate limiting, connection pooling restrictions, and HTTP/2 frame validation can provide additional defense-in-depth measures. The implementation of proper input sanitization and validation controls within the HTTP/2 parsing pipeline should include bounds checking, memory allocation limits, and graceful error recovery procedures. Security monitoring should be enhanced to detect unusual patterns in HTTP/2 header processing that could indicate exploitation attempts, while also implementing automated systems to track and remediate vulnerable components across the enterprise infrastructure.