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CVE-2020-15222

Replay of private_key_jwt possible in ORY Fosite

8.1 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.87%Unchanged since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 8.1

Replay of private_key_jwt possible in ORY Fosite

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.

Record
CVE-2020-15222
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Weakness
CWE-287
Updated
2026-11-02
EUVDEUVD-2021-1195 8.1

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.

Record
EUVD-2021-1195
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-v3q9-2p3m-7g43 8.1

Token reuse in Ory fosite

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"}

Patches

This issue is patched in 0.31.0.

Workarounds

Do not allow clients to use private_key_jwt.

References

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

Record
GHSA-v3q9-2p3m-7g43
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Weakness
CWE-287, CWE-345
Updated
2026-11-02
NVD 8.1

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.

Record
CVE-2020-15222
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
CVSS 2.0
5.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:N
Weakness
CWE-287, CWE-345
Updated
2026-11-02
OSV 8.1

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.

Record
CVE-2020-15222
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Updated
2026-11-02
OSVGHSA-v3q9-2p3m-7g43 8.1

Token reuse in Ory fosite

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"}

Patches

This issue is patched in 0.31.0.

Workarounds

Do not allow clients to use private_key_jwt.

References

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

Record
GHSA-v3q9-2p3m-7g43
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Weakness
CWE-287, CWE-345
Updated
2026-11-02
OSVGO-2021-0110 No score

Token reuse in github.com/ory/fosite

Uniqueness of JWT IDs (jti) are not checked, allowing the JWT to be replayed.

Record
GO-2021-0110
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/ory/fosite
Go
 before 0.31.0
0.31.0

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-15222 is a high vulnerability (CVSS 8.1) in Ory Fosite, published September 24, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.87%, the 58th percentile. Fixed in github.com/ory/fosite 0.31.0.

References

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