CVE-2023-36820 is a medium-severity (CVSS 4.8) CWE-284 vulnerability in io.micronaut.security:micronaut-security-oauth2. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2023-36820 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
micronaut security has invalid IdTokenClaimsValidator logic on aud
Real-World Exposure
io.micronaut.security:micronaut-security-oauth2☕io.micronaut.security:micronaut-security-oauth2☕io.micronaut.security:micronaut-security-oauth2☕io.micronaut.security:micronaut-security-oauth2☕io.micronaut.security:micronaut-security-oauth2☕io.micronaut.security:micronaut-security-oauth2☕io.micronaut.security:micronaut-security-oauth2☕io.micronaut.security:micronaut-security-oauth2+3 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Micronaut Security is a security solution for applications. Prior to versions 3.1.2, 3.2.4, 3.3.2, 3.4.3, 3.5.3, 3.6.6, 3.7.4, 3.8.4, 3.9.6, 3.10.2, and 3.11.1, IdTokenClaimsValidator skips aud claim validation if token is issued by same identity issuer/provider. Any OIDC setup using Micronaut where multiple OIDC applications exists for the same issuer but token auth are not meant to be shared. This issue has been patched in versions 3.1.2, 3.2.4, 3.3.2, 3.4.3, 3.5.3, 3.6.6, 3.7.4, 3.8.4, 3.9.6, 3.10.2, and 3.11.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.micronaut.security:micronaut-security-oauth2 | ≥ 3.11.0&&< 3.11.1 | 3.11.1 |
| ☕Maven | io.micronaut.security:micronaut-security-oauth2 | ≥ 3.10.0&&< 3.10.2 | 3.10.2 |
| ☕Maven | io.micronaut.security:micronaut-security-oauth2 | ≥ 3.9.0&&< 3.9.6 | 3.9.6 |
| ☕Maven | io.micronaut.security:micronaut-security-oauth2 | ≥ 3.8.0&&< 3.8.4 | 3.8.4 |
| ☕Maven | io.micronaut.security:micronaut-security-oauth2 | ≥ 3.7.0&&< 3.7.4 | 3.7.4 |
| ☕Maven | io.micronaut.security:micronaut-security-oauth2 | ≥ 3.6.0&&< 3.6.6 | 3.6.6 |
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 io.micronaut.security:micronaut-security-oauth2. 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 io.micronaut.security:micronaut-security-oauth2 to 3.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-36820 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-2023-36820 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-2023-36820. 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-2023-36820 in your dependencies?
O3 detects CVE-2023-36820 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.