CVE-2022-21698

client_golang is the instrumentation library for Go applications in Prometheus, and the promhttp package in client_golang provides tooling around HTTP servers and clients. In client_golang prior to version 1.11.1, HTTP server is susceptible to a Denial of Service through unbounded cardinality, and potential memory exhaustion, when handling requests with non-standard HTTP methods. In order to be affected, an instrumented software must use any of `promhttp.InstrumentHandler*` middleware except `RequestsInFlight`; not filter any specific methods (e.g GET) before middleware; pass metric with `method` label name to our middleware; and not have any firewall/LB/proxy that filters away requests with unknown `method`. client_golang version 1.11.1 contains a patch for this issue. Several workarounds are available, including removing the `method` label name from counter/gauge used in the InstrumentHandler; turning off affected promhttp handlers; adding custom middleware before promhttp handler that will sanitize the request method given by Go http.Request; and using a reverse proxy or web application firewall, configured to only allow a limited set of methods.

client_golang is the instrumentation library for Go applications in Prometheus, and the promhttp package in client_golang provides tooling around HTTP servers and clients. In client_golang prior to version 1.11.1, HTTP server is susceptible to a Denial of Service through unbounded cardinality, and potential memory exhaustion, when handling requests with non-standard HTTP methods. In order to be affected, an instrumented software must use any of `promhttp.InstrumentHandler*` middleware except `RequestsInFlight`; not filter any specific methods (e.g GET) before middleware; pass metric with `method` label name to our middleware; and not have any firewall/LB/proxy that filters away requests with unknown `method`. client_golang version 1.11.1 contains a patch for this issue. Several workarounds are available, including removing the `method` label name from counter/gauge used in the InstrumentHandler; turning off affected promhttp handlers; adding custom middleware before promhttp handler that will sanitize the request method given by Go http.Request; and using a reverse proxy or web application firewall, configured to only allow a limited set of methods.

The Prometheus client_golang HTTP server is vulnerable to a denial of service attack when handling requests with non-standard HTTP methods. In order to be affected, an instrumented software must use any of the promhttp.InstrumentHandler* middleware except RequestsInFlight; not filter any specific methods (e.g GET) before middleware; pass a metric with a "method" label name to a middleware; and not have any firewall/LB/proxy that filters away requests with unknown "method".

This is the Go client library for Prometheus. It has two separate parts, one for instrumenting application code, and one for creating clients that talk to the Prometheus HTTP API. client_golang is the instrumentation library for Go applications in Prometheus, and the promhttp package in client_golang provides tooling around HTTP servers and clients. ### Impact HTTP server susceptible to a Denial of Service through unbounded cardinality, and potential memory exhaustion, when handling requests with non-standard HTTP methods. ### Affected Configuration In order to be affected, an instrumented software must * Use any of `promhttp.InstrumentHandler*` middleware except `RequestsInFlight`. * Do not filter any specific methods (e.g GET) before middleware. * Pass metric with `method` label name to our middleware. * Not have any firewall/LB/proxy that filters away requests with unknown `method`. ### Patches * https://github.com/prometheus/client_golang/pull/962 * https://github.com/prometheus/client_golang/pull/987 ### Workarounds If you cannot upgrade to [v1.11.1 or above](https://github.com/prometheus/client_golang/releases/tag/v1.11.1), in order to stop being affected you can: * Remove `method` label name from counter/gauge you use in the InstrumentHandler. * Turn off affected promhttp handlers. * Add custom middleware before promhttp handler that will sanitize the request method given by Go http.Request. * Use a reverse proxy or web application firewall, configured to only allow a limited set of methods. ### For more information If you have any questions or comments about this advisory: * Open an issue in https://github.com/prometheus/client_golang * Email us at `prometheus-team@googlegroups.com`

client_golang es la biblioteca de instrumentación para aplicaciones Go en Prometheus, y el paquete promhttp en client_golang proporciona herramientas en torno a los servidores y clientes HTTP. En client_golang versiones anteriores a 1.11.1, el servidor HTTP es susceptible de una Denegación de Servicio mediante una cardinalidad no limitada, y un potencial agotamiento de la memoria, cuando es manejado peticiones con métodos HTTP no estándar. Para ser afectado, un software instrumentado debe usar cualquiera de los middleware "promhttp.InstrumentHandler*" excepto "RequestsInFlight"; no filtrar ningún método específico (por ejemplo GET) antes del middleware; pasar la métrica con el nombre de la etiqueta "method" a nuestro middleware; y no presentar ningún firewall/LB/proxy que filtre las peticiones con "method" desconocido. client_golang versión 1.11.1 contiene un parche para este problema. Se presentan varias medidas de mitigación disponibles, incluyendo la eliminación del nombre de la etiqueta "method" del contador/calibre usado en el InstrumentHandler; la deshabilitación de los manejadores promhttp afectados; la adición de un middleware personalizado antes del manejador promhttp que sanee el método de petición dado por Go http.Request; y el uso de un proxy inverso o un firewall de aplicaciones web, configurado para permitir sólo un conjunto limitado de métodos