CVE-2026-33996: LibJWT is a C JSON Web Token Library

Routine

MEDIUM 5.5UPGRADE

CVE-2026-33996 is a medium-severity flaw (CVSS 5.5) affecting libjwt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sourc

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 95%)
CISA exploited list	No
Weakness	CWE-476
Published	2026-03-27
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: libjwt

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

Am I affected?

Timeline

2026-03-27 23:17 UTCPublished CVE record published
2026-06-17 10:38 UTCUpdated Record last modified

libjwt libjwt UPGRADE

Affected: >= 3.0.0 and < 3.3.0

Fixed in: 3.3.0

Safe to downgrade to: a release before 3.0.0

1. Check installed version

apt-cache policy libjwt || rpm -q libjwt || libjwt --version

2. UPGRADE to 3.3.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libjwt

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libjwt

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.0.0 (Debian / Ubuntu)

apt-cache madison libjwt sudo apt install libjwt=<VERSION_BEFORE_3.0.0> sudo apt-mark hold libjwt

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libjwt sudo dnf downgrade libjwt-<VERSION_BEFORE_3.0.0> sudo dnf versionlock add libjwt

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-2026-33996?

libjwt: upgrade to 3.3.0. Exact commands for each OS are on this page.

Is CVE-2026-33996 being exploited?

CVE-2026-33996 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-2026-33996 affect?

CVE-2026-33996 affects libjwt. Severity is medium (CVSS 5.5). LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could expl

How urgent is CVE-2026-33996?

Priority 20/100. No elevated risk signals yet.

References

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