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.
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Remediation
No vendor fix or workaround currently provided.
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Tracking
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References
History
Wed, 30 Sep 2026 21:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | PyJWT.decode() reintroduces options-dict mutation, enabling silent claim-verification bypass on dict reuse | |
| Weaknesses | CWE-471 | |
| References |
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| Metrics |
cvssV3_1
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Subscriptions
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-09-30T21:17:58.116Z
Reserved: 2026-09-29T20:46:08.335Z
Link: CVE-2026-103001
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OpenCVE Enrichment
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Weaknesses
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CWE-471
Modification of Assumed-Immutable Data (MAID)