CVE-2026-87853
Received
Received - Intake
SSSD IdP Authentication Provider Prefix Comparison Flaw
Vulnerability report for CVE-2026-87853, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-09
Last updated on: 2026-09-09
Assigner: redhat-SADP
Description
Description
A flaw was found in SSSD's IdP authentication provider. The eval_access_token_buf() function compares the OIDC subject identifier using strncmp() with the authenticated user'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's identifier can authenticate as the target user.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| redhat | sssd | * |
| red_hat | sssd | to 2.11.0 (inc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-187 | The product performs a comparison that only examines a portion of a factor before determining whether there is a match, such as a substring, leading to resultant weaknesses. |
