CVE-2023-47633 in Traefik
Summary
by MITRE • 12/04/2023
Traefik is an open source HTTP reverse proxy and load balancer. The traefik docker container uses 100% CPU when it serves as its own backend, which is an automatically generated route resulting from the Docker integration in the default configuration. This issue has been addressed in versions 2.10.6 and 3.0.0-beta5. Users are advised to upgrade. There are no known workarounds for this vulnerability.
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Analysis
by VulDB Data Team • 12/05/2023
The vulnerability identified as CVE-2023-47633 affects Traefik, a popular open-source HTTP reverse proxy and load balancer that is widely deployed in containerized environments. This issue specifically manifests when Traefik operates as its own backend within Docker container deployments, creating a problematic scenario where the proxy consumes 100% CPU resources. The vulnerability stems from the default Docker integration configuration that automatically generates routes, leading to an infinite loop or recursive processing when Traefik attempts to route traffic to itself. This behavior represents a critical performance degradation issue that can severely impact system availability and resource utilization in production environments.
The technical flaw occurs due to improper handling of self-referencing routes within Traefik's Docker integration module. When the Traefik container is configured to monitor Docker containers for service discovery, it automatically creates routing rules that can inadvertently reference the Traefik container itself. This creates a situation where incoming requests are continuously routed through the proxy to itself, resulting in a CPU-intensive feedback loop. The issue is classified under CWE-691 as an Insufficient Control Flow Management, where the control flow mechanism fails to properly handle recursive or self-referencing scenarios. The vulnerability specifically impacts Traefik versions prior to 2.10.6 and 3.0.0-beta5, where the route generation logic did not adequately prevent or detect self-referencing configurations.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially causing complete system outages in containerized deployments. When Traefik consumes 100% CPU resources, it becomes unresponsive to legitimate traffic, effectively creating a denial of service condition for all applications behind the proxy. This issue is particularly dangerous in production environments where Traefik serves as a critical infrastructure component for routing traffic to multiple microservices. The vulnerability affects organizations using Traefik in Docker environments, which represents a significant portion of modern containerized deployments. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 (Endpoint Denial of Service) and T1566.001 (Phishing with Social Engineering) as it can be exploited to disrupt services and potentially used in broader attack chains targeting infrastructure availability.
Organizations affected by CVE-2023-47633 should prioritize upgrading to Traefik versions 2.10.6 or 3.0.0-beta5, as these releases contain the necessary fixes to prevent the recursive routing behavior that causes the CPU exhaustion. The vulnerability does not have any known workarounds since the issue is embedded within the core routing logic of the Docker integration module. Security teams should conduct immediate assessments of their Traefik deployments to identify instances where the proxy might be configured to route to itself, particularly in environments where Traefik is deployed as a sidecar container or where service discovery is enabled. The fix implemented in the patched versions addresses the root cause by introducing proper validation and filtering mechanisms to prevent self-referencing routes from being created during Docker integration processing. Organizations should also review their Docker deployment configurations to ensure that Traefik is not inadvertently configured to monitor its own container events, which would trigger the problematic route generation behavior.