CVE-2025-30157 in Envoy
Summary
by MITRE • 03/21/2025
Envoy is a cloud-native high-performance edge/middle/service proxy. Prior to 1.33.1, 1.32.4, 1.31.6, and 1.30.10, Envoy's ext_proc HTTP filter is at risk of crashing if a local reply is sent to the external server due to the filter's life time issue. A known situation is the failure of a websocket handshake will trigger a local reply leading to the crash of Envoy. This vulnerability is fixed in 1.33.1, 1.32.4, 1.31.6, and 1.30.10.
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Analysis
by VulDB Data Team • 04/15/2025
The vulnerability described in CVE-2025-30157 affects Envoy, a widely-used cloud-native high-performance edge/middle/service proxy that serves as a critical component in modern microservices architectures and service meshes. This security flaw specifically impacts the ext_proc HTTP filter functionality within Envoy, representing a significant reliability issue that can lead to system-wide service disruption. The vulnerability manifests when a local reply is sent to an external server, creating a scenario where the filter's lifecycle management becomes problematic and ultimately results in proxy crashes. This issue is particularly concerning given Envoy's role as a foundational networking component that often operates at the edge of cloud environments and within critical service communication pathways. The vulnerability affects multiple release versions including 1.33.1, 1.32.4, 1.31.6, and 1.30.10, indicating it was present across several major releases and likely impacted numerous production deployments.
The technical root cause of this vulnerability lies in the improper lifecycle management of the ext_proc HTTP filter, which is designed to interface with external processing servers for advanced request/response manipulation. When a websocket handshake fails, the system generates a local reply that should normally be handled gracefully by the proxy. However, due to the filter's lifecycle issue, this local reply triggers an unexpected state where the filter attempts to access resources that have already been deallocated or are in an inconsistent state. This creates a classic use-after-free or dangling pointer scenario that leads to memory corruption and ultimately causes Envoy to crash. The specific triggering condition of websocket handshake failures makes this vulnerability particularly relevant in modern cloud environments where websocket connections are commonly used for real-time communication, API gateways, and streaming services. The vulnerability aligns with CWE-416, which addresses use-after-free conditions, and represents a failure in proper resource management within the proxy's filter chain architecture.
The operational impact of this vulnerability extends beyond simple service disruption, as it can compromise the availability and reliability of entire service mesh deployments. When Envoy crashes due to this issue, it affects all traffic flowing through that proxy instance, potentially causing cascading failures in distributed systems where multiple services depend on stable connectivity. The vulnerability is particularly dangerous in production environments where high availability is critical, as it can lead to unexpected outages that are difficult to diagnose and recover from. Attackers could potentially exploit this vulnerability by initiating websocket connection attempts that are designed to fail in specific ways, creating a denial-of-service scenario that affects the entire proxy infrastructure. The impact is further amplified in microservices architectures where Envoy instances serve as edge proxies for numerous downstream services, making a single crash capable of affecting multiple applications and business functions.
Mitigation strategies for this vulnerability require immediate deployment of the patched versions 1.33.1, 1.32.4, 1.31.6, and 1.30.10, which contain the necessary fixes for the ext_proc filter lifecycle management. Organizations should conduct thorough testing of these updates in staging environments before deploying to production to ensure compatibility with existing configurations and service requirements. Additionally, implementing monitoring and alerting for proxy crashes or restarts can help detect exploitation attempts or environmental conditions that may trigger the vulnerability. Security teams should also consider implementing rate limiting or connection pooling controls for websocket connections to reduce the likelihood of triggering the specific failure conditions that lead to crashes. From an ATT&CK perspective, this vulnerability aligns with techniques related to service disruption and system resource exhaustion, and organizations should include this in their threat modeling for cloud-native environments. The fix addresses the core issue by properly managing the filter's lifecycle and ensuring that local replies are handled without attempting to access invalid resources, thereby preventing the crash condition that was previously possible.