CVE-2020-15240: Regression in JWT Signature Validation
7.4
CVSS Score
3.1
Basic Information
CVE ID
GHSA ID
EPSS Score
0.26033%
CWE
Published
11/3/2020
Updated
5/4/2023
KEV Status
No
Technology
Ruby
Technical Details
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
---|---|---|---|
omniauth-auth0 | rubygems | >= 2.3.0, < 2.4.1 | 2.4.1 |
Vulnerability Intelligence
Miggo AI
Root Cause Analysis
The vulnerability stems from missing JWT signature validation
in the verify_signature
method. The pre-patch code (vulnerable versions) returns [key, alg] without calling JWT.decode
to verify cryptographic validity. The critical fix in commit fd3a14f
adds JWT.decode(key, true, ...)
which performs actual signature verification. The test cases added in the commit (e.g., 'should fail when RS256 token has invalid signature') confirm that signature validation
was previously missing. This function
is directly tied to the CWE-347 (Improper Verification of Cryptographic Signature) listed in the advisory.