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VulnerabilityPublished Updated

CVE-2026-33996: benmcollins libjwt · NULL Pointer Dereference

Affects benmcollins libjwtSource CVE Database V5

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Not known to be exploited · CVSS 5.8 Medium : upgrade to 3.3.0 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
5.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.3.0
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade libjwt and benmcollins/libjwt to 3.3.0.

Affected software

ProductAffectedFixed in
benmcollinslibjwtAffected
  • >=3.0.0 <3.3.0
Fixed in
  • 3.3.0
GitHubbenmcollins/libjwtpkg:github/benmcollins/libjwtOther threatsAffected
  • >=3.0.0 <3.3.0
Fixed in
  • 3.3.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in libjwt version 3.3.0. Users should upgrade to this version to remediate the vulnerability. Until upgrading, users should avoid importing JWK files from untrusted sources, use the jwk2key tool to validate JWK files before import, and if possible, avoid using JWK files with RSA-PSS keys. These steps reduce the risk of triggering the NULL pointer dereference.

Description

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 sources. Use the `jwk2key` tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.

References

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