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CVE-2026-120459VulnerabilityPublished Updated

python-jose through 3.5.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to

Affects python-joseSource GCVE Database

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Authoritative record:CVE-2026-120459· Critical 9.1

Not known to be exploited · CVSS 9.1 Critical.

Data as of 5 Nov 2026, 12:36 UTC

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

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.09.1
CNA (VulnCheck)CVSS 3.17.4
CNACVSS 4.09.1
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 2 Nov 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 5 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSpython-josepkg:deb/ubuntu/python-jose?arch=source&distro=nobleOther threatsAffected
  • =3.3.0+dfsg-4
Fixed in–
Ubuntu 22.04 LTSpython-josepkg:deb/ubuntu/python-jose?arch=source&distro=jammyOther threatsAffected
  • =3.3.0+dfsg-1
Fixed in–

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

AI-suggested

Until a fix is available, avoid using zero-length HMAC secrets and ensure verification keys are properly validated to prevent empty keys.

Description

python-jose versions through 3.5.0 have an authentication bypass vulnerability due to acceptance of zero-length HMAC secrets in HMACKey and CryptographyHMACKey. This allows unauthenticated attackers to forge JWTs with arbitrary claims if the verification key resolves to empty, such as an oct JWK with an empty key value.

References

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