Vulnerability in Jpadilla Pyjwt

CVE-2026-103001

PyJWT is a Python implementation of JSON Web Token standards. From 2.11.0 through 2.13.0, PyJWT's PyJWT._merge_options() method can modify a caller-supplied mutable options mapping when verify_signature is false. If an application reuses that same mapping for a later decode() or decode_complete() call and changes verify_signature to true, the mapping can retain false values for expiration, not-before, issued-at, audience, issuer, subject, and JWT ID checks. A signed token with invalid registered claims can then be accepted without disabling signature verification, but applications that create a fresh options mapping for each call are not affected.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (27.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 27.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

The 30-day trend appears once there are two daily scores.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-103001?
CVE-2026-103001 is a medium-severity vulnerability in Jpadilla Pyjwt, classified under Modification of Assumed-Immutable Data (MAID). CVSS score: 6.5/10. Published 2026-09-30.
How severe is CVE-2026-103001?
Medium severity. CVSS v3 base score is 6.5 out of 10.