What’s Vulnerable › Vulnerabilities

CVE-2023-43810: opentelemetry-instrumentation Denial of Service vulnerability due to unbound cardinality metrics

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-10-06 · updated 2026-06-17
• Weakness: CWE-400

Description

OpenTelemetry, also known as OTel for short, is a vendor-neutral open-source Observability framework for instrumenting, generating, collecting, and exporting telemetry data such as traces, metrics, logs. Autoinstrumentation out of the box adds the label `http_method` that has unbound cardinality. It leads to the server's potential memory exhaustion when many malicious requests are sent. HTTP method for requests can be easily set by an attacker to be random and long. In order to be affected program has to be instrumented for HTTP handlers and does not filter any unknown HTTP methods on the level of CDN, LB, previous middleware, etc. This issue has been patched in version 0.41b0.

Affected products

• open-telemetry opentelemetry-go: before 0.41b0 — fixed in 0.41b0

How to fix

Upgrade to a fixed version: open-telemetry opentelemetry-go 0.41b0. Check the vendor advisory for mitigations.

References

• https://github.com/open-telemetry/opentelemetry-python-contrib/commit/6007e0c013071e7f8b9612d3bc68aeb9d600d74e
• https://github.com/open-telemetry/opentelemetry-python-contrib/releases/tag/v0.41b0
• https://github.com/open-telemetry/opentelemetry-python-contrib/security/advisories/GHSA-5rv5-6h4r-h22v
• https://github.com/open-telemetry/opentelemetry-python-contrib/commit/6007e0c013071e7f8b9612d3bc68aeb9d600d74e
• https://github.com/open-telemetry/opentelemetry-python-contrib/releases/tag/v0.41b0
• https://github.com/open-telemetry/opentelemetry-python-contrib/security/advisories/GHSA-5rv5-6h4r-h22v

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