CVE-2022-21698: Uncontrolled Resource Consumption in promhttp

Vulnerability summary

CVE-2022-21698 is a high (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in fedoraproject extra_packages_for_enterprise_linux. EPSS estimates a 5.99% chance of exploitation in the next 30 days, higher than 93.3% of scored vulnerabilities.

Timeline

1. 15-02-2022
   PublishedVulnerability first disclosed.
2. 23-04-2025
   Last modifiedVulnerability information updated.

Description

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.

• CWE-400Uncontrolled Resource ConsumptionThe product does not properly control the allocation and maintenance of a limited resource.
• CWE-770Allocation of Resources Without Limits or ThrottlingThe product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.