CVE-2026-87853

Sssd: sssd: idp authentication prefix comparison allows cross-user impersonation

CVSS 3.1 7.5 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-87853

Published

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.

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Affected versions, risk and source history

Exploitation and risk

Source status

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Risk history

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Advisory history

5 saved versions

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11 Nov 2026 13:57:25 UTC