CVE-2026-45363 (GCVE-0-2026-45363)

Vulnerability from cvelistv5 – Published: 2026-07-14 21:32 – Updated: 2026-07-14 21:34
VLAI
Title
`jwt` (Ruby gem) - empty-key HMAC bypass
Summary
ruby-jwt is a Ruby implementation of the RFC 7519 OAuth JSON Web Token standard. Prior to 2.10.3 and 3.2.0, JWT.decode(token, '', true, algorithm: 'HS256') accepts an attacker-forged token because OpenSSL::HMAC.digest('SHA256', '', payload) returns a valid digest under an empty key and no empty-key precondition exists in the HMAC algorithm. The same path is reached when a keyfinder block or key_finder: argument returns an empty string, nil, or an array containing nil for an unknown key, affecting HS256, HS384, and HS512 verification through JWT.decode and JWT::EncodedToken#verify_signature!. This issue is fixed in versions 2.10.3 and 3.2.0.
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-287 - Improper Authentication
  • CWE-326 - Inadequate Encryption Strength
  • CWE-1391 - Use of Weak Credentials
Assigner
References
Impacted products
Vendor Product Version
jwt ruby-jwt Affected: < 2.10.3
Affected: >= 3.0.0, < 3.2.0
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        }
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          "url": "https://github.com/jwt/ruby-jwt/security/advisories/GHSA-c32j-vqhx-rx3x"
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      "source": {
        "advisory": "GHSA-c32j-vqhx-rx3x",
        "discovery": "UNKNOWN"
      },
      "title": "`jwt` (Ruby gem) - empty-key HMAC bypass"
    }
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    "cveId": "CVE-2026-45363",
    "datePublished": "2026-07-14T21:32:26.676Z",
    "dateReserved": "2026-05-12T00:51:29.085Z",
    "dateUpdated": "2026-07-14T21:34:05.174Z",
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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