CVE-2026-87853

Severity CVSS v4.0:

Pending analysis

Type:

Unavailable / Other

Publication date:

09/09/2026

Last modified:

09/10/2026

Description

A flaw was found in SSSD&#39;s IdP authentication provider. The eval_access_token_buf() function compares the OIDC subject identifier using strncmp() with the authenticated user&#39;s identifier length, performing a prefix comparison instead of an exact match. An attacker whose IdP identifier is a strict prefix of a target user&#39;s identifier can authenticate as the target user.

Impact

Vector 3.x

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

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

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

Base Score 3.x

7.50

Severity 3.x

HIGH

CVE-2026-87853

Description

Impact

References to Advisories, Solutions, and Tools