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GHSA-3p3g-vpw6-4w66

MEDIUM

GHSA-3p3g-vpw6-4w66 is a medium-severity (CVSS 5.8) CWE-294 vulnerability in github.com/ory/hydra. O3 Security confirms whether GHSA-3p3g-vpw6-4w66 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Authentication Bypass in hydra

Also known asCVE-2020-5300GO-2022-0786
Published
May 27, 2021
Updated
Jul 8, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

Blast Radius

1 pkg affected
🐹github.com/ory/hydra

Real-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

When using client authentication method "private_key_jwt" [1], 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. Here is me sending the same token request twice, hence with the same jti assertion, and getting two access tokens:

$ curl --insecure --location --request POST 'https://localhost/_/oauth2/token' \
   --header 'Content-Type: application/x-www-form-urlencoded' \
   --data-urlencode 'grant_type=client_credentials' \
   --data-urlencode 'client_id=c001d00d-5ecc-beef-ca4e-b00b1e54a111' \
   --data-urlencode 'scope=application openid' \
   --data-urlencode 'client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer' \
   --data-urlencode 'client_assertion=eyJhb [...] jTw'
{"access_token":"zeG0NoqOtlACl8q5J6A-TIsNegQRRUzqLZaYrQtoBZQ.VR6iUcJQYp3u_j7pwvL7YtPqGhtyQe5OhnBE2KCp5pM","expires_in":3599,"scope":"application openid","token_type":"bearer"}⏎            ~$ curl --insecure --location --request POST 'https://localhost/_/oauth2/token' \
   --header 'Content-Type: application/x-www-form-urlencoded' \
   --data-urlencode 'grant_type=client_credentials' \
   --data-urlencode 'client_id=c001d00d-5ecc-beef-ca4e-b00b1e54a111' \
   --data-urlencode 'scope=application openid' \
   --data-urlencode 'client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer' \
   --data-urlencode 'client_assertion=eyJhb [...] jTw'
{"access_token":"wOYtgCLxLXlELORrwZlmeiqqMQ4kRzV-STU2_Sollas.mwlQGCZWXN7G2IoegUe1P0Vw5iGoKrkOzOaplhMSjm4","expires_in":3599,"scope":"application openid","token_type":"bearer"}

Severity

We rate the severity as medium because the following reasons make it hard to replay tokens without the patch:

  • TLS protects against MITM which makes it difficult to intercept valid tokens for replay attacks
  • The expiry time of the JWT gives only a short window of opportunity where it could be replayed

Patches

This will be patched with v1.4.0+oryOS.17

Workarounds

Two workarounds have been identified:

  • Do not allow clients to use private_key_jwt
  • Use short expiry times for the JWTs

References

https://openid.net/specs/openid-connect-core-1_0.html#ClientAuthentication

Upstream

This issue will be resolved in the upstream repository https://github.com/ory/fosite

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/ory/hydraall versions1.4.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ory/hydra. 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.

  2. Fix

    Update github.com/ory/hydra to 1.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3p3g-vpw6-4w66 is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 pinpoints whether GHSA-3p3g-vpw6-4w66 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-3p3g-vpw6-4w66. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact When using client authentication method "private_key_jwt" [1], 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. Here is me sending the same token request twice, hence with the same `jti` assertion, and getting two access tokens: ``` $ curl --insecure --location --request POST 'https://localhost/_/oauth2/token' \ --
O3 Security · Impact-Aware SCA

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