GHSA-5rv5-6h4r-h22v
HIGHopentelemetry-instrumentation Denial of Service vulnerability due to unbound cardinality metrics
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
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 | 0.41b0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for opentelemetry-instrumentation. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update opentelemetry-instrumentation to 0.41b0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5rv5-6h4r-h22v is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-5rv5-6h4r-h22v is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-5rv5-6h4r-h22v. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-5rv5-6h4r-h22v in your dependencies?
O3 detects GHSA-5rv5-6h4r-h22v across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.