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CVE-2020-15240

Regression in JWT Signature Validation

7.4 HighFix available

omniauth-auth0 (rubygems) versions >= 2.3.0 and < 2.4.1 improperly validate the JWT token signature when using the jwt_validator.verify method. Improper validation of the JWT token signature can allow an attacker to bypass authentication and authorization. You are affected by this vulnerability if all of the following conditions apply: 1. You are using omniauth-auth0. 2. You are using JWTValidator.verify method directly OR you are not authenticating using the SDK’s default Authorization Code Flow. The issue is patched in version 2.4.1.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.80%Unchanged since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 7.4

Regression in JWT Signature Validation

omniauth-auth0 (rubygems) versions >= 2.3.0 and < 2.4.1 improperly validate the JWT token signature when using the jwt_validator.verify method. Improper validation of the JWT token signature can allow an attacker to bypass authentication and authorization. You are affected by this vulnerability if all of the following conditions apply: 1. You are using omniauth-auth0. 2. You are using JWTValidator.verify method directly OR you are not authenticating using the SDK’s default Authorization Code Flow. The issue is patched in version 2.4.1.

Record
CVE-2020-15240
CVSS 3.1
7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-287, CWE-347
Updated
2026-11-02
EUVDEUVD-2020-1445 7.4

omniauth-auth0 (rubygems) versions >= 2.3.0 and < 2.4.1 improperly validate the JWT token signature when using the jwt_validator.verify method. Improper validation of the JWT token signature can allow an attacker to bypass authentication and authorization. You are affected by this vulnerability if all of the following conditions apply: 1. You are using omniauth-auth0. 2. You are using JWTValidator.verify method directly OR you are not authenticating using the SDK’s default Authorization Code Flow. The issue is patched in version 2.4.1.

Record
EUVD-2020-1445
CVSS 3.1
7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-58r4-h6v8-jcvm 7.4

Regression in JWT Signature Validation

Overview

Versions after and including 2.3.0 are improperly validating the JWT token signature when using the JWTValidator.verify method. Improper validation of the JWT token signature when not using the default Authorization Code Flow can allow an attacker to bypass authentication and authorization.

Am I affected?

You are affected by this vulnerability if all of the following conditions apply:

  • You are using omniauth-auth0.
  • You are using JWTValidator.verify method directly OR you are not authenticating using the SDK’s default Authorization Code Flow.

How to fix that?

Upgrade to version 2.4.1.

Will this update impact my users?

The fix provided in this version will not affect your users.

Record
GHSA-58r4-h6v8-jcvm
CVSS 3.1
7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-287, CWE-347
Updated
2026-11-02
NVD 7.4

omniauth-auth0 (rubygems) versions >= 2.3.0 and < 2.4.1 improperly validate the JWT token signature when using the jwt_validator.verify method. Improper validation of the JWT token signature can allow an attacker to bypass authentication and authorization. You are affected by this vulnerability if all of the following conditions apply: 1. You are using omniauth-auth0. 2. You are using JWTValidator.verify method directly OR you are not authenticating using the SDK’s default Authorization Code Flow. The issue is patched in version 2.4.1.

Record
CVE-2020-15240
CVSS 3.1
7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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-347
Updated
2026-11-02
OSV 9.1

omniauth-auth0 (rubygems) versions >= 2.3.0 and < 2.4.1 improperly validate the JWT token signature when using the jwt_validator.verify method. Improper validation of the JWT token signature can allow an attacker to bypass authentication and authorization. You are affected by this vulnerability if all of the following conditions apply: 1. You are using omniauth-auth0. 2. You are using JWTValidator.verify method directly OR you are not authenticating using the SDK’s default Authorization Code Flow. The issue is patched in version 2.4.1.

Record
CVE-2020-15240
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Updated
2026-11-02
OSVGHSA-58r4-h6v8-jcvm 7.4

Regression in JWT Signature Validation

Overview

Versions after and including 2.3.0 are improperly validating the JWT token signature when using the JWTValidator.verify method. Improper validation of the JWT token signature when not using the default Authorization Code Flow can allow an attacker to bypass authentication and authorization.

Am I affected?

You are affected by this vulnerability if all of the following conditions apply:

  • You are using omniauth-auth0.
  • You are using JWTValidator.verify method directly OR you are not authenticating using the SDK’s default Authorization Code Flow.

How to fix that?

Upgrade to version 2.4.1.

Will this update impact my users?

The fix provided in this version will not affect your users.

Record
GHSA-58r4-h6v8-jcvm
CVSS 3.1
7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-287, CWE-347
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
omniauth-auth0
RubyGems
2.3.0 up to 2.4.1
2.4.1
omniauth-auth0
RubyGems
2.3.0 up to 2.4.1, plus listed versions
2.3.12.4.0
2.4.1

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-2020-15240 is a high vulnerability (CVSS 7.4) in Auth0 Omniauth-auth0, published October 21, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.80%, the 56th percentile. Fixed in omniauth-auth0 2.4.1.

References

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