Sssd: sssd: idp authentication prefix comparison allows cross-user impersonation
Historical advisory recorded 29 Oct 2026 06:47:47 UTC. Read the latest advisory.
cve-program · CVE-2026-87853
PublishedA 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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cve-program · CVE-2026-87853
PublishedSssd: sssd: idp authentication prefix comparison allows cross-user impersonation
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.
- Source published
- 9 Sep 2026 16:06:25 UTC
- Source modified
- 29 Oct 2026 05:30:43 UTC
- Saved here
- 29 Oct 2026 06:47:47 UTC
- Source terms
- CVE Program Terms of Use
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Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H