CVE-2022-21698 Uncontrolled Resource Consumption in promhttp

What is CVE-2022-21698?

CVE-2022-21698 is a high-severity denial of service vulnerability in Fedoraproject Extra Packages for Enterprise Linux, published on 15 Feb 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-770, CWE-400

Which versions are affected by CVE-2022-21698?

3 open source packages ship an affected version, including github.com/prometheus/client_golang. It affects 4 products.

Products include Fedoraproject Extra Packages for Enterprise Linux, Fedoraproject Fedora, Prometheus Client Golang, Rdo Project Rdo.

How do I fix CVE-2022-21698?

Upgrade github.com/prometheus/client_golang to 1.11.1 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2022-21698 being exploited?

There is no known exploitation of CVE-2022-21698 in the wild and no public exploit code.

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All Fedoraproject Extra Packages for Enterprise Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-31981, AZL-33567, AZL-33603, AZL-33611, AZL-33614, AZL-33618 and 45 more.