python-jose algorithm confusion guard bypassed by DER-encoded public keys
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | python-jose | <= 3.5.0 | no fix |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-85394
- https://github.com/mpdavis/python-jose/issues/414
- https://github.com/advisories/GHSA-6c5p-j8vq-pqhj
- https://github.com/mpdavis/python-jose
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/backends/native.py
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/utils.py
- https://www.vulncheck.com/advisories/python-jose-through-3.5.0-algorithm-confusion-via-der-encoded-public-key-as-hmac-secret
- https://nvd.nist.gov/vuln/detail/CVE-2024-33663
- https://github.com/mpdavis/python-jose/issues/346
- https://github.com/pypa/advisory-database/tree/main/vulns/python-jose/PYSEC-2024-232.yaml
- https://www.vicarius.io/vsociety/posts/algorithm-confusion-in-python-jose-cve-2024-33663
- https://pypi.org/project/python-jose
- https://github.com/advisories/GHSA-3qf3-8w2g-rqmx
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N- Weakness (CWE)
CWE-347, CWE-327- Platform
- Python (PyPI)
- Package
python-jose- Disclosed
- 26.04.2024
- Updated
- 15.10.2026 18:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2024-232 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-3qf3-8w2g-rqmx - CC BY 4.0
OSV / GitHub Advisory Database - GHSA-6c5p-j8vq-pqhj - CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-4298 - PyPA Advisory Database; CC BY 4.0
Vulnerability history: python-jose
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 01.2017 12.2025
- Without a fix
- 2
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- Medium 2
Disclosures per year
- 2017: 1
- 2018: 0
- 2019: 0
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 2
- 2025: 1
- 2026: 0
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