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JWE is missing AES-GCM authentication tag validation in encrypted JWE

Critical severity GitHub Reviewed Published Aug 7, 2025 in jwt/ruby-jwe • Updated Aug 8, 2025

Package

bundler jwe (RubyGems)

Affected versions

<= 1.1.0

Patched versions

1.1.1

Description

Overview

The authentication tag of encrypted JWEs can be brute forced, which may result in loss of confidentiality for those JWEs and provide ways to craft arbitrary JWEs.

Impact

  • JWEs can be modified to decrypt to an arbitrary value
  • JWEs can be decrypted by observing parsing differences
  • The GCM internal GHASH key can be recovered

Am I Affected?

You are affected by this vulnerability even if you do not use an AES-GCM encryption algorithm for your JWEs.

Patches

The version 1.1.1 fixes the issue by adding the tag length check for the AES-GCM algorithm.

Important: As the GHASH key could have leaked, you must rotate the encryption keys after upgrading to version 1.1.1.

References

Félix Charette talk at NorthSec 2025 about the issue

References

@anakinj anakinj published to jwt/ruby-jwe Aug 7, 2025
Published to the GitHub Advisory Database Aug 7, 2025
Reviewed Aug 7, 2025
Published by the National Vulnerability Database Aug 8, 2025
Last updated Aug 8, 2025

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(1st percentile)

Weaknesses

Improper Validation of Integrity Check Value

The product does not validate or incorrectly validates the integrity check values or checksums of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission. Learn more on MITRE.

CVE ID

CVE-2025-54887

GHSA ID

GHSA-c7p4-hx26-pr73

Source code

Credits

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