Traefik is an open source HTTP reverse proxy and load balancer. Versions prior to 2.9.6 are subject to a potential vulnerability in Traefik displaying the Authorization header in its debug logs. In certain cases, if the log level is set to DEBUG, credentials provided using the Authorization header are displayed in the debug logs. Attackers must have access to a users logging system in order for credentials to be stolen. This issue has been addressed in version 2.9.6. Users are advised to upgrade. Users unable to upgrade may set the log level to `INFO`, `WARN`, or `ERROR`.

Traefik (pronounced traffic) is a modern HTTP reverse proxy and load balancer that assists in deploying microservices. There is a potential vulnerability in Traefik managing HTTP/2 connections. A closing HTTP/2 server connection could hang forever because of a subsequent fatal error. This failure mode could be exploited to cause a denial of service. There has been a patch released in versions 2.8.8 and 2.9.0-rc5. There are currently no known workarounds.

Traefik is an HTTP reverse proxy and load balancer. Prior to version 2.6.1, Traefik skips the router transport layer security (TLS) configuration when the host header is a fully qualified domain name (FQDN). For a request, the TLS configuration choice can be different than the router choice, which implies the use of a wrong TLS configuration. When sending a request using FQDN handled by a router configured with a dedicated TLS configuration, the TLS configuration falls back to the default configuration that might not correspond to the configured one. If the CNAME flattening is enabled, the selected TLS configuration is the SNI one and the routing uses the CNAME value, so this can skip the expected TLS configuration. Version 2.6.1 contains a patch for this issue. As a workaround, one may add the FDQN to the host rule. However, there is no workaround if the CNAME flattening is enabled.

Traefik is an HTTP reverse proxy and load balancer. Prior to version 2.4.13, there exists a potential header vulnerability in Traefik's handling of the Connection header. Active exploitation of this issue is unlikely, as it requires that a removed header would lead to a privilege escalation, however, the Traefik team has addressed this issue to prevent any potential abuse. If one has a chain of Traefik middlewares, and one of them sets a request header, then sending a request with a certain Connection header will cause it to be removed before the request is sent. In this case, the backend does not see the request header. A patch is available in version 2.4.13. There are no known workarounds aside from upgrading.

Traefik before 2.4.5 allows the loading of IFRAME elements from other domains.

In Traefik before versions 1.7.26, 2.2.8, and 2.3.0-rc3, there exists a potential open redirect vulnerability in Traefik's handling of the "X-Forwarded-Prefix" header. The Traefik API dashboard component doesn't validate that the value of the header "X-Forwarded-Prefix" is a site relative path and will redirect to any header provided URI. Successful exploitation of an open redirect can be used to entice victims to disclose sensitive information. Active Exploitation of this issue is unlikely as it would require active header injection, however the Traefik team addressed this issue nonetheless to prevent abuse in e.g. cache poisoning scenarios.

Traefik 2.x, in certain configurations, allows HTTPS sessions to proceed without mutual TLS verification in a situation where ERR_BAD_SSL_CLIENT_AUTH_CERT should have occurred.

configurationwatcher.go in Traefik 2.x before 2.1.4 and TraefikEE 2.0.0 mishandles the purging of certificate contents from providers before logging.

types/types.go in Containous Traefik 1.7.x through 1.7.11, when the --api flag is used and the API is publicly reachable and exposed without sufficient access control (which is contrary to the API documentation), allows remote authenticated users to discover password hashes by reading the Basic HTTP Authentication or Digest HTTP Authentication section, or discover a key by reading the ClientTLS section. These can be found in the JSON response to a /api request.

Containous Traefik 1.6.x before 1.6.6, when --api is used, exposes the configuration and secret if authentication is missing and the API's port is publicly reachable.