CVE-2026-4349
MEDIUMDuende IdentityServer Token Renewal Endpoint authorize improper authentication
Title source: cnaDescription
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.
References (3)
Core 3
Core References
Vdb Entry, Technical Description vdb-entry
technical-description
VDB-351380 | Duende IdentityServer Token Renewal Endpoint authorize improper authentication
https://vuldb.com/?id.351380
Signature, Permissions Required signature
permissions-required
VDB-351380 | CTI Indicators (IOB, IOC, IOA)
https://vuldb.com/?ctiid.351380
Third Party Advisory third-party-advisory
Submit #772071 | DuendeSoftware Identity Server 4 Authentication Bypass Issues
https://vuldb.com/?submit.772071
Scores
CVSS v3
5.6
EPSS
0.0041
EPSS Percentile
32.2%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-287
Status
published
Products (4)
Duende/IdentityServer
4
Duende/IdentityServer4
4.1.0
Duende/IdentityServer4
4.1.1
Duende/IdentityServer4
4.1.2
Published
Mar 17, 2026
Tracked Since
Mar 18, 2026