python-jose through 3.5.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to
Affects python-joseSource GCVE Database
Not known to be exploited · CVSS 9.1 Critical.
Data as of 5 Nov 2026, 12:36 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 9.1 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 7.4 |
| CNA | CVSS 4.0 | 9.1 |
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 2 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSpython-josepkg:deb/ubuntu/python-jose?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSpython-josepkg:deb/ubuntu/python-jose?arch=source&distro=jammyOther threats | Affected
| 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
- ubuntu.com/security/CVE-2026-120459 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-120459 (opens in a new tab)
- github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/cryptography_backend.py (opens in a new tab)
- github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/native.py (opens in a new tab)
- github.com/mpdavis/python-jose/issues/398 (opens in a new tab)
- vulncheck.com/advisories/python-jose-through-3.5.0-authentication-bypass-via-empty-hmac-key (opens in a new tab)