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VulnerabilityPublished Updated

CVE-2026-44699: From 3.0.0 to 3.3.2, libjwt accepts an RSA JWK that does not contain an alg parameter as the

Affects libjwtSource GCVE Database

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Authoritative record:CVE-2026-44699· Critical 9.1

Not known to be exploited · CVSS 9.1 Critical · fixed in 3.3.3 : patch libjwt as a priority.

Data as of 13 Nov 2026, 13:10 UTC

CVSS 4.0 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
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 13 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10libjwtpkg:deb/ubuntu/libjwt?arch=source&distro=stonkingOther threatsAffected
  • =1.17.2-1build1
  • =1.17.2-1build2
Fixed in–
Ubuntu 26.10libjwt3pkg:deb/ubuntu/libjwt3?arch=source&distro=stonkingOther threatsAffected
  • =3.2.3-1
  • =3.3.3-1
  • =3.3.3-1build1
Fixed in–
Ubuntu 26.04 LTSlibjwtpkg:deb/ubuntu/libjwt?arch=source&distro=resoluteOther threatsAffected
  • =1.17.2-1
  • =1.17.2-1build1
Fixed in–
Ubuntu 26.04 LTSlibjwt3pkg:deb/ubuntu/libjwt3?arch=source&distro=resoluteOther threatsAffected
  • =3.2.2-1
  • =3.2.3-1
Fixed in–
Ubuntu 25.10libjwtpkg:deb/ubuntu/libjwt?arch=source&distro=questingOther threatsAffected
  • =1.17.2-1
Fixed in–
Ubuntu 24.04 LTSlibjwtpkg:deb/ubuntu/libjwt?arch=source&distro=nobleOther threatsAffected
  • 1.10.2-1build1 – 1.17.0-2build2
4 affected builds
Fixed in–

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

AI-suggested

Upgrade libjwt to version 3.3.3 or later, where this vulnerability is fixed. No other mitigation is indicated or required by the vendor advisory.

Description

LibJWT versions from 3.0.0 to 3.3.2 have a vulnerability where RSA JSON Web Keys (JWKs) missing the 'alg' parameter are accepted as verification keys for HS256/HS384/HS512 tokens. This leads to HMAC verification using a zero-length key in the OpenSSL backend, allowing attackers to forge valid JWTs without the secret or RSA private key. The issue is fixed in version 3.3.3.

References

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