jpadilla PyJWT up to 2.13.0 Options Merging PyJWT._merge_options verify_signature signature verification

Summaryinfo

A vulnerability classified as critical was found in jpadilla PyJWT up to 2.13.0. This impacts the function PyJWT._merge_options of the component Options Merging. Such manipulation of the argument verify_signature leads to signature verification. This vulnerability is traded as CVE-2026-103001. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in jpadilla PyJWT up to 2.13.0. Affected by this issue is the function PyJWT._merge_options of the component Options Merging. The manipulation of the argument verify_signature with an unknown input leads to a signature verification vulnerability. Using CWE to declare the problem leads to CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-103001 since 09/29/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/30/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• jpadilla

Name

• PyJWT

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13.0

Website

• Product: https://github.com/jpadilla/pyjwt/

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