title: Issuer not verified from obtained token in user_oidc
description: user_oidc provides the OIDC connect user backend for Nextcloud, an open-source cloud platform. Starting in version 1.0.0 and prior to version 1.3.3, missing verification of the issuer would have allowed an attacker to perform a man-in-the-middle attack returning corrupted or known token they also have access to. user_oidc 1.3.3 contains a patch. No known workarounds are available.
problem types: CWE-303: Incorrect Implementation of Authentication Algorithm
affected:
{
vendor: nextcloud
product: security-advisories
versions:
version: >= 1.0.0, < 1.3.3, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 4.8
baseSeverity: MEDIUM
confidentialityImpact: LOW
integrityImpact: LOW
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
version: 3.1
]