CVE-2020-15222 is a high-severity (CVSS 8.1) Improper Authentication vulnerability in github.com/ory/fosite. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2020-15222 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Token reuse in Ory fosite
Real-World Exposure
github.com/ory/fositeReal-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
In ORY Fosite (the security first OAuth2 & OpenID Connect framework for Go) before version 0.31.0, when using "private_key_jwt" authentication the uniqueness of the jti value is not checked. When using client authentication method "private_key_jwt", OpenId specification says the following about assertion jti: "A unique identifier for the token, which can be used to prevent reuse of the token. These tokens MUST only be used once, unless conditions for reuse were negotiated between the parties". Hydra does not seem to check the uniqueness of this jti value. This problem is fixed in version 0.31.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/ory/fosite | all versions | 0.31.0 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ory/fosite. 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/ory/fosite to 0.31.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15222 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-2020-15222 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-2020-15222. 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-2020-15222 in your dependencies?
O3 detects CVE-2020-15222 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.