CVE-2026-87853

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-09. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
7.5
EG Score
7.5(high)
EG Risk
34(Track)
EG Risk 34/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
21%
KEV
Not listed

Published

September 9, 2026

Last Modified

September 10, 2026

Advisory Details (2)

Auto-updated Sep 9, 2026
Patch available. Sources: redhat.
redhat

2530888 – (CVE-2026-87853) CVE-2026-87853 sssd: sssd: IdP authentication prefix comparison allows cross-user impersonation

https://bugzilla.redhat.com/show_bug.cgi?id=2530888
redhat Patch Available

CVE-2026-87853 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 10.2 is the first and only RHEL version that ships the IdP provider feature. RHEL 10.1, despite shippi

https://access.redhat.com/security/cve/CVE-2026-87853

Vendor Advisories for CVE-2026-87853(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 25× in last 7d / 41× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 01:37 UTCEG score recompute
  2. 2026-09-19 01:37 UTCGHSA enrichment
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 13:44 UTCGHSA enrichment
  5. 2026-09-18 01:51 UTCEG score recompute
  6. 2026-09-18 01:51 UTCGHSA enrichment
  7. 2026-09-17 19:32 UTCEPSS rescore
  8. 2026-09-17 13:58 UTCGHSA enrichment
  9. 2026-09-17 02:05 UTCGHSA enrichment
  10. 2026-09-16 14:11 UTCEG score recompute
  11. 2026-09-16 14:11 UTCGHSA enrichment
  12. 2026-09-16 14:09 UTCEPSS rescore
  13. 2026-09-16 05:15 UTCEPSS rescore
  14. 2026-09-16 02:17 UTCGHSA enrichment
  15. 2026-09-15 14:24 UTCEG score recompute
  16. 2026-09-15 14:24 UTCGHSA enrichment
  17. 2026-09-15 03:12 UTCEPSS rescore
  18. 2026-09-15 02:30 UTCGHSA enrichment
  19. 2026-09-14 14:34 UTCGHSA enrichment
  20. 2026-09-14 02:41 UTCEG score recompute
  21. 2026-09-14 02:41 UTCGHSA enrichment
  22. 2026-09-13 14:47 UTCGHSA enrichment
  23. 2026-09-13 02:50 UTCEG score recompute
  24. 2026-09-13 02:50 UTCGHSA enrichment
  25. 2026-09-12 14:57 UTCGHSA enrichment
Show 16 more
  1. 2026-09-12 03:04 UTCGHSA enrichment
  2. 2026-09-11 15:09 UTCEG score recompute
  3. 2026-09-11 15:09 UTCGHSA enrichment
  4. 2026-09-11 14:53 UTCEPSS rescore
  5. 2026-09-11 14:53 UTCEPSS rescore
  6. 2026-09-11 03:15 UTCGHSA enrichment
  7. 2026-09-10 15:22 UTCEG score recompute
  8. 2026-09-10 15:22 UTCGHSA enrichment
  9. 2026-09-10 15:00 UTCEG score recompute
  10. 2026-09-10 15:00 UTCGHSA enrichment
  11. 2026-09-10 08:29 UTCGHSA enrichment
  12. 2026-09-09 20:36 UTCEG score recompute
  13. 2026-09-09 20:35 UTCGHSA enrichment
  14. 2026-09-09 17:28 UTCEG score recompute
  15. 2026-09-09 16:28 UTCEG score recompute
  16. 2026-09-09 16:25 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-87853?
CVE-2026-87853 is a high vulnerability published on September 9, 2026. A flaw was found in SSSD's IdP authentication provider. The evalaccesstoken_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…
When was CVE-2026-87853 disclosed?
CVE-2026-87853 was first published in the National Vulnerability Database on September 9, 2026, with the most recent update on September 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-87853 actively exploited?
CVE-2026-87853 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 79.2% of all scored CVEs.
What is the CVSS score of CVE-2026-87853?
CVE-2026-87853 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-87853?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-87853, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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