What’s Vulnerable › Vulnerabilities

CVE-2020-15222: Replay of private_key_jwt possible in ORY Fosite

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-09-24 · updated 2026-06-17
• Weakness: CWE-287

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 products

• ory fosite: before 0.31.0 — fixed in 0.31.0

How to fix

Upgrade to a fixed version: ory fosite 0.31.0. Check the vendor advisory for mitigations.

References

• https://github.com/ory/fosite/commit/0c9e0f6d654913ad57c507dd9a36631e1858a3e9
• https://github.com/ory/fosite/security/advisories/GHSA-v3q9-2p3m-7g43
• https://openid.net/specs/openid-connect-core-1_0.html#ClientAuthentication
• https://github.com/ory/fosite/commit/0c9e0f6d654913ad57c507dd9a36631e1858a3e9
• https://github.com/ory/fosite/security/advisories/GHSA-v3q9-2p3m-7g43
• https://openid.net/specs/openid-connect-core-1_0.html#ClientAuthentication

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