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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-45363

39
FAUCET Score

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.

First published: Jul 14, 2026Last modified: Jul 14, 2026

Impacted Technologies

VendorProductVersion(s)CPE
JwtRuby-Jwt
< 2.10.3, >= 3.0.0, < 3.2.0CNA affected

CVSS Data

CVSS version used by this source: 3.1

9.1CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.24%
Probability of exploitation in next 30 days
EPSS Percentile
15.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0024 is in the 1st percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

rubygemspatch availablevia ghsa
Product: jwtFixed in: 3.2.0
rubygemspatch availablevia ghsa
Product: jwtFixed in: 2.10.3

Vendor Advisories (1)

rubygemsGHSA-c32j-vqhx-rx3xhigh

ruby-jwt: Empty-key HMAC bypass; cross-language sibling of CVE-2026-44351

May 18, 2026

References

github.com / jwt/ruby-jwt/commit/9820020869ad147b941e49d96ab8beba35532964
github.com / jwt/ruby-jwt/commit/db560b769a07bd9724e77ff505011ac01872106f
github.com / jwt/ruby-jwt/releases/tag/v2.10.3
github.com / jwt/ruby-jwt/releases/tag/v3.2.0
github.com / jwt/ruby-jwt/security/advisories/GHSA-c32j-vqhx-rx3x