What’s Vulnerable › Vulnerabilities

CVE-2026-103001: PyJWT.decode() reintroduces options-dict mutation, enabling silent claim-verification bypass on dict reuse

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-30 · updated 2026-10-08
• Weakness: CWE-471

Description

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.

Affected products

• jpadilla pyjwt: from 2.11.0 before 2.13.0 — fixed in 2.13.0

How to fix

Upgrade to a fixed version: jpadilla pyjwt 2.13.0. Check the vendor advisory for mitigations.

References

• https://github.com/jpadilla/pyjwt/commit/0c87c8c8b1a74cac99ad8115f3050efcb7fbed35
• https://github.com/jpadilla/pyjwt/issues/679
• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-gvp8-978c-rx2q
• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-gvp8-978c-rx2q

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