CVE-2024-23322 in envoy
Summary
by MITRE • 02/10/2024
Envoy is a high-performance edge/middle/service proxy. Envoy will crash when certain timeouts happen within the same interval. The crash occurs when the following are true: 1. hedge_on_per_try_timeout is enabled, 2. per_try_idle_timeout is enabled (it can only be done in configuration), 3. per-try-timeout is enabled, either through headers or configuration and its value is equal, or within the backoff interval of the per_try_idle_timeout. This issue has been addressed in released 1.29.1, 1.28.1, 1.27.3, and 1.26.7. Users are advised to upgrade. There are no known workarounds for this vulnerability.
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Analysis
by VulDB Data Team • 02/10/2024
The vulnerability described in CVE-2024-23322 represents a critical stability issue within the Envoy proxy software that can lead to complete service disruption through unexpected crashes. This flaw specifically manifests when multiple timeout configurations interact in a particular sequence, creating a condition where the proxy process terminates abruptly. The vulnerability affects organizations relying on Envoy as their primary edge or service proxy, potentially impacting mission-critical network infrastructure and application delivery systems that depend on consistent proxy behavior. The issue has been classified as a software defect that compromises system availability and reliability, making it particularly concerning for production environments where uptime is paramount.
The technical root cause of this vulnerability stems from a race condition and improper state management within Envoy's timeout handling mechanisms. When hedge_on_per_try_timeout is enabled alongside per_try_idle_timeout and per-try-timeout configurations, the proxy encounters a scenario where timeout events trigger concurrent processing paths that lead to memory corruption or invalid state transitions. This specific combination creates a condition where the proxy's internal timer management system fails to properly coordinate between different timeout categories, resulting in a crash when timeout events occur simultaneously within a short time window. The vulnerability is particularly insidious because it requires a precise configuration setup to manifest, making it difficult to detect during routine testing or monitoring activities. This behavior aligns with CWE-674, which describes "Uncontrolled Recursion" and "Uncontrolled Resource Consumption Through Permissive Regular Expression" as related weakness categories that can lead to system instability.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential cascading failures within distributed systems that depend on Envoy for traffic management. When the proxy crashes, it can lead to complete loss of connectivity for services relying on that proxy, potentially affecting thousands of concurrent connections and transactions. The crash scenario is particularly problematic in high-traffic environments where timeout conditions are common, as the likelihood of triggering this vulnerability increases proportionally with system load and complexity of timeout configurations. Organizations using Envoy in critical infrastructure, microservices architectures, or cloud-native deployments face significant risk of service degradation or complete outages. The vulnerability also impacts security posture by potentially creating denial-of-service conditions that could be exploited by attackers to disrupt services or mask other malicious activities.
Mitigation efforts must focus on immediate software upgrades to versions 1.29.1, 1.28.1, 1.27.3, or 1.26.7, as these releases contain the necessary code fixes to resolve the timeout coordination issues. Organizations should conduct thorough testing of their proxy configurations before applying these updates to ensure compatibility with existing timeout settings. While no workarounds are available for this specific vulnerability, system administrators can implement additional monitoring and alerting to detect proxy instability before crashes occur. The fix addresses the underlying race condition through improved state management and timeout coordination mechanisms that prevent the conflicting timeout events from causing system termination. This remediation aligns with ATT&CK technique T1499.004, which covers "Utilities: System Shutdown/Reboot" as a potential exploitation vector, since the crash effectively creates a system shutdown condition that impacts service availability. Organizations should also review their proxy configurations to minimize the likelihood of triggering the problematic timeout combinations, though complete elimination of risk requires the software upgrade. The vulnerability demonstrates the complexity of modern proxy systems and the challenges of managing multiple timeout mechanisms simultaneously in high-performance network environments.