Authentication bypass via empty-key HMAC verification
Published Jul 14, 2026 · Updated Jul 14, 2026
Authentication bypass in JWT ruby-jwt before 2.10.3 and 3.0.0 through 3.1.2 allows remote attackers to forge HMAC-signed tokens. JWT::JWA::Hmac coerces nil verification keys to an empty string and accepts empty strings, allowing OpenSSL to validate attacker-generated HS256, HS384, or HS512 digests. Exploitation requires an application to pass an empty key or return one from a key finder; nonempty static keys and key finders that reject misses are unaffected.
Summary
What happened
Authentication bypass in JWT ruby-jwt before 2.10.3 and 3.0.0 through 3.1.2 allows remote attackers to forge HMAC-signed tokens. JWT::JWA::Hmac coerces nil verification keys to an empty string and accepts empty strings, allowing OpenSSL to validate attacker-generated HS256, HS384, or HS512 digests. Exploitation requires an application to pass an empty key or return one from a key finder; nonempty static keys and key finders that reject misses are unaffected.
The record
- CVE
- CVE-2026-45363
- Published
- Jul 14, 2026
- Updated
- Jul 14, 2026
- Vendor
- JWT
- Product
- ruby-jwt
- Classifications
- CWE-287, CWE-326, CWE-1391, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 14, 2026CVE publishedPublication date reported by the CVE source.
- Jul 14, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 2.10.3
- Affected versionversion=>= 3.0.0, < 3.2.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GitHub advisory empty-key token forgery reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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