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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-103001
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-30 22:16:33 UTC
Updated2026-09-30 22:16:33 UTC
DescriptionPyJWT 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

Problem Types: CWE-471 | CWE-471 CWE-471: Modification of Assumed-Immutable Data (MAID)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Jpadilla Pyjwt affected >= 2.11.0, <= 2.13.0 Not specified

References

ReferenceSourceLinkTags
github.com/jpadilla/pyjwt/commit/0c87c8c8b1a74cac99ad8115f3050efcb7fbed35 [email protected] github.com
github.com/jpadilla/pyjwt/issues/679 [email protected] github.com
github.com/jpadilla/pyjwt/security/advisories/GHSA-gvp8-978c-rx2q [email protected] github.com
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