CVE-2026-87853
HIGHDescription
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.
How to fix
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Moderate risk: more likely to be exploited than 45% of all known CVEs.
References
Related Vulnerabilities
Other CWE-187 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-41110 | Critical | 9.9 | 16% | - | Fix |
| CVE-2022-31802 | Critical | 9.8 | 1.3% | - | Fix |
| CVE-2026-35031 | Critical | 9.9 | 0.9% | - | Fix |
| CVE-2024-39742 | High | 8.1 | 0.8% | - | Fix |
| CVE-2026-84376 | Medium | 6.3 | 0.7% | - | Fix |
| CVE-2026-62750 | High | 6.5 | 0.7% | - | Fix |
Common questions
How do I fix CVE-2026-87853?
Published advisories record a fix for 114 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-87853 being actively exploited?
Not that we know of. CVE-2026-87853 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.56% is the estimated probability that it will be exploited in the next 30 days. That is higher than 45% of all scored CVEs.
How severe is CVE-2026-87853?
CVE-2026-87853 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-87853 affect?
Published advisories record a fix for libipa_hbac (Red Hat / RHEL), libipa_hbac (Rocky), libipa_hbac-debuginfo (Red Hat / RHEL), libipa_hbac-debuginfo (Rocky), and 110 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-09.