CVE-2026-4349

Severity CVSS v4.0:

MEDIUM

Type:

CWE-287 Authentication Issues

Publication date:

17/03/2026

Last modified:

18/03/2026

Description

A vulnerability was determined in Duende IdentityServer 4. 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. The vendor was contacted early about this disclosure but did not respond in any way.

Impact

Vector 4.0

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 CVSS v4.0 Severity and Metrics:

Base Score: 6.30 MEDIUM
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

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

Base Score 4.0

6.30

Severity 4.0

MEDIUM

Vector 3.x

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L CVSS v3.1 Severity and Metrics:

Base Score: 5.60 MEDIUM
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector (AV): Network
Attack Complexity (AC): High
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): Low
Integrity (I): Low
Availability (A): Low

Base Score 3.x

5.60

Severity 3.x

MEDIUM

Vector 2.0

AV:N/AC:H/Au:N/C:P/I:P/A:P CVSS v2.0 Severity and Metrics:

Base Score: 5.10 MEDIUM
Vector: AV:N/AC:H/Au:N/C:P/I:P/A:P

Attack Vector (AV): Network
Attack Complexity (AC): High
Authentication (Au): None
Confidentiality (C): Physical
Integrity (I): Physical
Availability (A): Physical

Base Score 2.0

5.10

Severity 2.0

MEDIUM

CVE-2026-4349

Description

Impact

References to Advisories, Solutions, and Tools