PyJWT: Public keys in DER form are accepted as HMAC secrets, bypassing the CVE-2022-29217 guard — GHSA-P4G4-X82P-Q773

Summary

### Summary `HMACAlgorithm.prepare_key` blocks asymmetric keys from being used as HMAC secrets by searching for text markers only. It looks for `-----BEGIN` and for an `ssh-` prefix. The same key in DER form is binary ASN.1 and has neither marker, so it passes the check and is used as an HMAC secret. An application that verifies tokens with an RSA or EC public key, and also allows HS256 with that same key, can be…

Timeline

Published by source

2026-09-29

Risk context

• Reported severity or threat level: high.
• Reported CVSS score: 7.4 out of 10.
• Reported EPSS value: 0.00175.
• Review exposure for the affected product or family: pip: pyjwt.

Product

pip: pyjwt

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-P4G4-X82P-Q773

Source

GitHub

Vendor

GitHub

Published by source

2026-09-29

Last source activity

2026-09-29

Additional identifiers

CVE-2026-102271

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.