GHSA-9c54-x2g4-v92j
MEDIUMGHSA-9c54-x2g4-v92j is a medium-severity (CVSS 5.9) CWE-770 vulnerability in github.com/sigstore/timestamp-authority/v2. O3 Security confirms whether GHSA-9c54-x2g4-v92j is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Sigstore Timestamp Authority has OOM due to unbounded metric label cardinality
Exploitation Status
No confirmed exploitation observed yet
- 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 GHSA-9c54-x2g4-v92j.
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.
How urgent is this, really
GHSA-9c54-x2g4-v92j plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 372,296 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/sigstore/timestamp-authority/v2🐹github.com/sigstore/timestamp-authorityReal-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
Impact
An unauthenticated remote attacker can trigger unbounded memory growth on the timestamp authority server.
This vulnerability exists because the global wrapMetrics middleware records the raw HTTP request path (r.URL.Path) and raw HTTP request method (r.Method) as Prometheus labels for latency and request count metric vectors. Since this middleware runs before standard routing occurs, it executes for all incoming requests, including those for unmatched paths (yielding 404 responses) or arbitrary request methods. The Prometheus library registers a new, permanent time-series entry for every distinct label combination. An attacker can continuously issue requests containing random paths (e.g., /api/v1/timestamp/<uuid>) or random HTTP methods to exhaust system memory.
Patches
This issue has been patched by limiting the metric label values to a strict allowlist of expected paths (/ping, /api/v1/timestamp, /api/v1/timestamp/certchain) and expected HTTP methods (GET, POST, HEAD, OPTIONS). Unrecognized paths or methods are normalized to a static string ("unrecognized").
Users should update to version v2.0.7 or later.
Workarounds
- Block or drop incoming requests with invalid HTTP methods or unknown request paths at a reverse proxy or load balancer before they reach the timestamp authority server.
- Configure rate-limiting on the public interface to prevent remote attackers from issuing millions of unique requests in a short duration.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/sigstore/timestamp-authority/v2 | all versions | 2.1.0 |
| 🐹Go | github.com/sigstore/timestamp-authority | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/timestamp-authority/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/sigstore/timestamp-authority/v2 to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9c54-x2g4-v92j 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-9c54-x2g4-v92j 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-9c54-x2g4-v92j. 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-9c54-x2g4-v92j in your dependencies?
O3 detects GHSA-9c54-x2g4-v92j across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.