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Fencer Vulns
high 8.4

CVE-2023-51774 json

json-jwt allows bypass of identity checks via a sign/encryption confusion attack

published 2023-12-25 2 y ago modified 2026-09-10 1 mo ago also GHSA-c8v6-786g-vjx6 , EUVD-2024-0613

cvss
8.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits
0
none known

Summary

The json-jwt (aka JSON::JWT) gem 1.16.3 for Ruby sometimes allows bypass of identity checks via a sign/encryption confusion attack. For example, JWE can sometimes be used to bypass JSON::JWT.decode.

Patch / fix

  • rubygems json-jwt 1.15.3.1, 1.16.6
  • rubygem-json-jwt Package Hub 15 SP5, openSUSE Leap 15.5 1.16.6-bp155.3.3.1
  • rubygem-aes_key_wrap Package Hub 15 SP5, openSUSE Leap 15.5 1.1.0-bp155.2.1

opensuse advisories openSUSE-SU-2025:0004-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-51774 updated cvss 6.5

json-jwt: bypass of identity checks via a sign/encryption confusion attack

  • Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/fluentd-rhel8
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/P3ngu1nW/CVE_Request/blob/main/novjson-jwt.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.4 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 8.4 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
rubygems json-jwt
>=1.16.0, <1.16.6
<1.15.3.1
1.16.6
1.15.3.1

Affected products

  • json-jwt_project json-jwt

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.