CVE-2026-70616 in boringproxy
Summary
by MITRE • 08/05/2026
boringproxy through 0.10.0 contains a resource exhaustion vulnerability that allows any authenticated user to permanently exhaust server file descriptors, goroutines, and memory by sending requests to the GET /loading endpoint with attacker-supplied id query parameter values. Because the handler performs no map-lookup validity check and receives on a nil channel that blocks forever, with no timeout, no context cancellation, and no server-side reclamation due to absent HTTP server timeouts, each malicious request permanently holds one goroutine, one file descriptor, and approximately 50 kB of memory until the server's file descriptor limit is reached and listener Accept calls fail, halting all tunnel traffic forwarding for all users.
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Analysis
by VulDB Data Team • 08/05/2026
The boringproxy vulnerability represents a critical resource exhaustion flaw that fundamentally undermines system availability and operational integrity. This issue affects versions through 0.10.0 and demonstrates a classic denial-of-service attack vector through improper resource management. The vulnerability manifests specifically when authenticated users send crafted requests to the GET /loading endpoint with malicious id query parameters, creating a scenario where server resources become permanently consumed without any mechanism for automatic cleanup or recovery.
The technical implementation of this flaw reveals fundamental design shortcomings in the HTTP handler logic. The system performs no validation checks on map lookups or input parameter validity, allowing arbitrary values to flow directly into critical resource allocation paths. More concerning is the deliberate use of nil channel operations that block indefinitely without any timeout mechanisms or context cancellation protocols. This architectural choice creates a permanent state where each malicious request consumes one goroutine, one file descriptor, and approximately 50 kilobytes of memory. The absence of server-side timeouts and HTTP server timeout configurations eliminates any automatic resource reclamation, creating a scenario where resources are permanently tied up until the system reaches its fundamental limits.
The operational impact of this vulnerability extends far beyond simple service disruption, as it creates cascading failures that affect all users of the tunneling service. When the server's file descriptor limit is reached, subsequent listener Accept calls begin to fail, effectively halting all tunnel traffic forwarding operations for every connected user. This represents a complete system failure mode where legitimate users experience immediate and prolonged service outages while malicious actors can maintain their resource consumption indefinitely. The vulnerability operates at the core of the application's concurrency model, exploiting the fundamental assumptions about resource lifetime management and garbage collection within the go runtime environment.
Security practitioners should recognize this issue as a direct violation of several established security principles and frameworks including CWE-400 which addresses resource exhaustion vulnerabilities, and aligns with ATT&CK technique T1499.1 for network denial of service attacks. The vulnerability demonstrates poor input validation practices that can be traced back to CWE-20, representing improper input validation in the parameter handling logic. Organizations should implement immediate mitigations including request rate limiting, explicit timeout configurations, and proper resource cleanup mechanisms. Additionally, the system architecture requires fundamental redesign to prevent nil channel operations without proper error handling and to establish automatic resource reclamation protocols that prevent indefinite resource consumption patterns.
The root cause analysis reveals that this vulnerability stems from inadequate consideration of resource lifecycle management within concurrent programming paradigms. Proper implementation would include context.WithTimeout or context.WithCancel operations, explicit map lookup validation, and server configuration parameters that enforce reasonable resource limits. The absence of these protective mechanisms creates a situation where the system cannot recover from malicious input patterns, making it vulnerable to sustained attack scenarios that can completely compromise service availability. This vulnerability serves as a stark reminder of the critical importance of defensive programming practices in concurrent systems and the need for comprehensive testing of resource management behaviors under various load conditions.