CVE-2026-4349 MEDIUM

CVE-2026-4349: Duende IdentityServer4 Token Renewal Endpoint authorize improper authentication

Vendor Duende
Product IdentityServer4
Weakness CWE-287 · Improper authentication
Published March 17, 2026
Last update March 25, 2026

CVSS base score

6.3/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X

What the vulnerability does

01Description

A vulnerability was determined in Duende IdentityServer4 up to 4.1.2. The affected element is an unknown function of the file /connect/authorize of the component Token Renewal Endpoint. This manipulation of the argument id_token_hint causes improper authentication. It is possible to initiate the attack remotely. The attack is considered to have high complexity. The exploitability is described as difficult. This vulnerability only affects products that are no longer supported by the maintainer.

Key dates

02Disclosure timeline

March 17, 2026 CVE published
March 25, 2026 Record updated

Related vulnerabilities

04Related CVE