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VulnerabilityPublished

CVE-2026-44699: benmcollins libjwt · Weak Cryptography

Affects benmcollins libjwtSource CVE Database V5

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Not known to be exploited · CVSS 9.1 Critical : upgrade to 3.3.3 as a priority.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.3.3
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 May 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 3.3.3.

Affected software

ProductAffectedFixed in
benmcollinslibjwtAffected
  • >=3.0.0 <3.3.3
Fixed in
  • 3.3.3
GitHubbenmcollins/libjwtpkg:github/benmcollins/libjwtOther threatsAffected
  • <3.3.3 >=3.0.0
Fixed in
  • 3.3.3

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

AI-suggested

This vulnerability is fixed in libjwt version 3.3.3. Since libjwt is used as a cloud-hosted service, the vendor manages remediation server-side. Users should verify with the vendor advisory that their environment is updated to version 3.3.3 or later. Patch status is confirmed by the vendor fix. No additional mitigation actions are required if the environment is updated accordingly.

Description

LibJWT is a C JSON Web Token Library. From 3.0.0 to 3.3.2, libjwt accepts an RSA JWK that does not contain an alg parameter as the verification key for an HS256/HS384/HS512 token. In the OpenSSL backend, this causes HMAC verification to run with a zero-length key, so an attacker can forge a valid JWT without knowing any secret or RSA private key. This is an algorithm-confusion authentication bypass. It affects applications that load RSA keys from JWKS where alg is omitted, which is valid JWK syntax and common in real deployments, and then choose the verification algorithm from the JWT header, for example in a kid lookup callback. This vulnerability is fixed in 3.3.3.

References

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