Vulnerability in Red Hat Enterprise Linux 10
CVE-2026-87853
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.003 (25.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 25.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.003 · change: -0.001
Affected products
Weakness classification (CWE)
References
- access.redhat.com/security/cve/CVE-2026-87853 (vdb-entry)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking)
- access.redhat.com/errata/RHSA-2026:77534 (vendor-advisory)
Frequently asked questions
- What is CVE-2026-87853?
- CVE-2026-87853 is a high-severity vulnerability in Red Hat Enterprise Linux 10, classified under Partial String Comparison. CVSS score: 7.5/10. Published 2026-09-09.
- How severe is CVE-2026-87853?
- High severity. CVSS v3 base score is 7.5 out of 10.