CVE-2023-43810 — opentelemetry-instrumenta…
HIGHFix: open-telemetry/opentelemetry-python-contrib@6007e0cCVE-2023-43810 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in opentelemetry-instrumentation. A fix is available for opentelemetry-instrumentation — see the affected versions and patch details below.
opentelemetry-instrumentation Denial of Service vulnerability due to unbound cardinality metrics
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-43810.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
opentelemetry-instrumentationReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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.
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 - introduce the variable OTEL_INSTRUMENTATION_HTTP_CAPTURE_ALL_METHODS that will allow enabling current behavior when someone really wants it.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | opentelemetry-instrumentation | all versions | 0.41b0pip install --upgrade 'opentelemetry-instrumentation==0.41b0' |
Affected Products
opentelemetryopentelemetryDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for opentelemetry-instrumentation, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update opentelemetry-instrumentation to 0.41b0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-43810 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2023-43810 in your dependencies?
Find it across PyPI, including transitive dependencies.