opentelemetry-instrumentation Denial of Service vulnerability due to unbound cardinality metrics

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2023-43810: 0.84% estimated exploitation activity in the next 30 days; percentile 58.03 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Autoinstrumentation out of the box adds the label httpmethod that has unbound cardinality. It leads to the server's potential memory exhaustion when many malicious requests are sent. Details HTTP method for requests can be easily set by an attacker to be random and long. PoC Send many requests with long randomly generated HTTP methods and observe how memory consumption increases during it. The app can be like this example from the official docs. Impact 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. Proposed solution For convenience and safe usage of this library, it should by default mark with the label UNKNOWN non-standard HTTP methods to show that such requests were made (and this way does not increase cardinality). In case someone wants to stay with the current behavior, library API should allow it. The mechanism with environment variables can be reused…

Published by the source

2 Oct 2023, 23:29 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:12 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-5rv5-6h4r-h22v

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-5rv5-6h4r-h22v

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# Patch Next advisory brief: CVE-2023-43810

Advisory: opentelemetry-instrumentation Denial of Service vulnerability due to unbound cardinality metrics
IDs: CVE-2023-43810, GHSA-5rv5-6h4r-h22v
Record: https://patchnext.com/advisories/cve-2023-43810 (revision 2, source checked 26 Oct 2026, 13:12 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: opentelemetry-instrumentation 0.41b0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI opentelemetry-instrumentation: affected < 0.41b0; fixed in 0.41b0

## Suggested inspection (read-only)
- `python -m pip show opentelemetry-instrumentation`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on opentelemetry-instrumentation.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-5rv5-6h4r-h22v (OSV record GHSA-5rv5-6h4r-h22v lists affected ranges: PyPI opentelemetry-instrumentation >=0 <0.41b0 (fixed))
- Verified: https://github.com/advisories/GHSA-5rv5-6h4r-h22v (GitHub-reviewed advisory GHSA-5rv5-6h4r-h22v lists affected ranges: PyPI opentelemetry-instrumentation >=0 <0.41b0)

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