GHSA-8m2x-3m6q-6w8j
MEDIUMGHSA-8m2x-3m6q-6w8j is a medium-severity (CVSS 4.3) CWE-863 vulnerability in github.com/nats-io/nats-server/v2. O3 Security confirms whether GHSA-8m2x-3m6q-6w8j is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
NATS: Message tracing can be redirected to arbitrary subject
Real-World Exposure
github.com/nats-io/nats-server/v2🐹github.com/nats-io/nats-server/v2Real-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
Background
NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing.
The nats-server supports telemetry on messages, using the per-message NATS headers.
Problem Description
A valid client which uses message tracing headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to which the client does not have publish permission.
The payload is a valid trace message and not chosen by the attacker.
Affected Versions
Any version before v2.12.6 or v2.11.15
Workarounds
None.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/nats-io/nats-server/v2 | ≥ 2.11.0&&< 2.11.15 | 2.11.15 |
| 🐹Go | github.com/nats-io/nats-server/v2 | ≥ 2.12.0-preview.1&&< 2.12.6 | 2.12.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/nats-io/nats-server/v2. 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/nats-io/nats-server/v2 to 2.11.15 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8m2x-3m6q-6w8j 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-8m2x-3m6q-6w8j 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-8m2x-3m6q-6w8j. 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-8m2x-3m6q-6w8j in your dependencies?
O3 detects GHSA-8m2x-3m6q-6w8j across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.