CVE-2026-85394python-jose through 3.5.0 Algorithm Confusion via DER-encoded Public Key as HMAC Secret
Updated under an hour ago ()
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It affects mpdavis python-jose. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- Weakness (CWE)
- CWE-347
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Deferred
- Record last updated
- Sep 14, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
mpdavis python-jose mpdavis:python_jose (from the name) | through 3.5.0 | CNA record |
References
- https://github.com/mpdavis/python-jose/issues/414issue-tracking
- https://github.com/mpdavis/python-joseproduct
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/backends/native.pytechnical-description
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/utils.pytechnical-description
- https://github.com/advisories/GHSA-6c5p-j8vq-pqhjrelated
- https://www.vulncheck.com/advisories/python-jose-through-3.5.0-algorithm-confusion-via-der-encoded-public-key-as-hmac-secretthird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.