CVE-2026-85394python-jose through 3.5.0 Algorithm Confusion via DER-encoded Public Key as HMAC Secret
- 9.3CriticalCVSS base score
- 0.22%Exploitation in 30 daysEPSS · top 87% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
python-jose through 3.5.0 fails to properly validate asymmetric keys in HMAC initialization, accepting DER-encoded public keys that lack PEM armor or SSH prefixes. Attackers holding the service's public key can forge HS256 tokens that pass verification when algorithms are not explicitly restricted. This is an incomplete fix for CVE-2024-33663.
Timeline
ID reserved
By VulnCheck
Published
- 11 days later
· 11 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| VulnCheckCNA (assigner) | 4.0 | Critical9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N |
| VulnCheckCNA (assigner) | 3.1 | Critical9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| NVDNVD · Deferred | 4.0 | Critical9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.22% · top 87% of all CVEs (15 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.3.
Affected products
- affected ≤ 3.5.0
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- PyPIpython-joseGHSA-3qf3-8w2g-rqmx (opens in a new tab)
References
References6
- GitHub Issue #414 (opens in a new tab)issue-tracking
- https://github.com/mpdavis/python-jose (opens in a new tab)product
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/backends/native.py (opens in a new tab)technical-description
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/utils.py (opens in a new tab)technical-description
- GitHub Security Advisory (GHSA-6c5p-j8vq-pqhj) (opens in a new tab)related
- VulnCheck Advisory: python-jose through 3.5.0 Algorithm Confusion via DER-encoded Public Key as HMAC Secret (opens in a new tab)third-party-advisory
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-70671 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-3qf3-8w2g-rqmx (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-85394)Record last updated .