Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-28802

Severity CVSS v4.0:
HIGH
Type:
Unavailable / Other
Publication date:
06/03/2026
Last modified:
06/03/2026

Description

Authlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.. This issue has been patched in version 1.6.7.

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P CVSS v4.0 Severity and Metrics:

Base Score: 7.70 HIGH
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): None
Integrity (VI): High
Availability (VA): None
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None
Exploit Maturity (E): POC

Base Score 4.0
7.70
Severity 4.0
HIGH

References to Advisories, Solutions, and Tools