CVE-2021-41090
HIGHInstance config inline secret exposure in Grafana
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
github.com/grafana/agentReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Grafana Agent is a telemetry collector for sending metrics, logs, and trace data to the opinionated Grafana observability stack. Prior to versions 0.20.1 and 0.21.2, inline secrets defined within a metrics instance config are exposed in plaintext over two endpoints: metrics instance configs defined in the base YAML file are exposed at /-/config and metrics instance configs defined for the scraping service are exposed at /agent/api/v1/configs/:key. Inline secrets will be exposed to anyone being able to reach these endpoints. If HTTPS with client authentication is not configured, these endpoints are accessible to unauthenticated users. Secrets found in these sections are used for delivering metrics to a Prometheus Remote Write system, authenticating against a system for discovering Prometheus targets, and authenticating against a system for collecting metrics. This does not apply for non-inlined secrets, such as *_file based secrets. This issue is patched in Grafana Agent versions 0.20.1 and 0.21.2. A few workarounds are available. Users who cannot upgrade should use non-inline secrets where possible. Users may also desire to restrict API access to Grafana Agent with some combination of restricting the network interfaces Grafana Agent listens on through http_listen_address in the server block, configuring Grafana Agent to use HTTPS with client authentication, and/or using firewall rules to restrict external access to Grafana Agent's API.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/grafana/agent | ≥ 0.14.0&&< 0.21.2 | 0.21.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/grafana/agent. 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 github.com/grafana/agent to 0.21.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41090 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 CVE-2021-41090 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 CVE-2021-41090. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-41090 in your dependencies?
O3 detects CVE-2021-41090 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.