Authlib library contains a signature‑verification bypass vulnerability

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-96760
StatePUBLISHED
Assignercertcc
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-28 20:17:11 UTC
Updated2026-10-01 14:17:32 UTC
DescriptionAuthlib (v1.7.2 and below) contains a signature verification bypass vulnerability. The JsonWebSignature.deserialize_json() method accepts a JSON Serialization JWS object and returns the payload as successfully verified without checking for a signature and without requiring a cryptographic key.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from ADP

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

EPSS: 0.002780000 probability, percentile 0.184140000 (date 2026-10-04)

Problem Types: CWE-20 | CWE-347 | CWE-358 | CWE-670 | CWE-347 Improper Verification of Cryptographic Signature | CWE-670 Always-Incorrect Control Flow Implementation | CWE-358 Improperly Implemented Security Check for Standard | CWE-20 Improper Input Validation | CWE-347 CWE-347 Improper Verification of Cryptographic Signature | CWE-670 CWE-670 Always-Incorrect Control Flow Implementation | CWE-358 CWE-358 Improperly Implemented Security Check for Standard | CWE-20 CWE-20 Improper Input Validation

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Authlib Authlib affected 1.7.2 Not specified

References

ReferenceSourceLinkTags
github.com/authlib/authlib [email protected] github.com
kb.cert.org/vuls/id/762428 [email protected] kb.cert.org
www.kb.cert.org/vuls/id/762428 af854a3a-2127-422b-91ae-364da2661108 www.kb.cert.org
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