CVE-2023-51774: The json-jwt (aka JSON::JWT) gem 1.16.3 for Ruby sometimes allows bypass of identity checks via a sign/encrypt

Routine

HIGH 8.4DOWNGRADE

CVE-2023-51774 is a high-severity flaw (CVSS 8.4) affecting json-jwt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.4 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 86%)
CISA exploited list	No
Weakness	CWE-284
Published	2024-02-29
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: json-jwt project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2024-02-29 01:42 UTCPublished CVE record published
2026-06-17 06:41 UTCUpdated Record last modified

json-jwt project json-jwt DOWNGRADE

Affected: 1.16.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.16.3

1. Check installed version

apt-cache policy json-jwt || rpm -q json-jwt || json-jwt --version

2. No fixed release: DOWNGRADE to a release before 1.16.3 (Debian / Ubuntu)

apt-cache madison json-jwt sudo apt install json-jwt=<VERSION_BEFORE_1.16.3> sudo apt-mark hold json-jwt

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list json-jwt sudo dnf downgrade json-jwt-<VERSION_BEFORE_1.16.3> sudo dnf versionlock add json-jwt

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-51774?

json-jwt: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-51774 being exploited?

CVE-2023-51774 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-51774 affect?

CVE-2023-51774 affects json-jwt. Severity is high (CVSS 8.4). 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.

How urgent is CVE-2023-51774?

Priority 38/100. High severity; Public exploit reference

Software pages

Ruby vulnerabilities

References

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