CVE-2026-81906

MEDIUMPre-NVD 6.36.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
6.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.3Exploit: None knownExposed: 0

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

Concrete CMS OAuth callback login path prior to version 9.5.3 did not check whether an account was active or email-validated before establishing a session. A deactivated or unvalidated user with an existing OAuth binding could complete authentication and receive a session that was fully authenticated for the callback response, with the login recorded and login events dispatched. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

CVSS v3
6.3
EG Score
6.3(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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
Severity63% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
32%
KEV
Not listed

Published

September 10, 2026

Last Modified

September 11, 2026

References (1)

Vendor Advisories for CVE-2026-81906(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 21× in last 7d / 33× 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 22:38 UTCEG score recompute
  2. 2026-09-19 22:38 UTCGHSA enrichment
  3. 2026-09-19 00:31 UTCEG score recompute
  4. 2026-09-19 00:30 UTCGHSA enrichment
  5. 2026-09-18 19:28 UTCEPSS rescore
  6. 2026-09-18 02:22 UTCEG score recompute
  7. 2026-09-18 02:22 UTCGHSA enrichment
  8. 2026-09-17 04:15 UTCEG score recompute
  9. 2026-09-17 04:15 UTCGHSA enrichment
  10. 2026-09-16 14:08 UTCEPSS rescore
  11. 2026-09-16 06:07 UTCEG score recompute
  12. 2026-09-16 06:07 UTCGHSA enrichment
  13. 2026-09-16 05:15 UTCEPSS rescore
  14. 2026-09-15 08:00 UTCEG score recompute
  15. 2026-09-15 08:00 UTCGHSA enrichment
  16. 2026-09-15 03:12 UTCEPSS rescore
  17. 2026-09-15 03:12 UTCEPSS rescore
  18. 2026-09-14 09:52 UTCEG score recompute
  19. 2026-09-14 09:51 UTCGHSA enrichment
  20. 2026-09-13 11:43 UTCEG score recompute
  21. 2026-09-13 11:43 UTCGHSA enrichment
  22. 2026-09-12 13:36 UTCGHSA enrichment
  23. 2026-09-11 15:29 UTCEG score recompute
  24. 2026-09-11 15:29 UTCGHSA enrichment
  25. 2026-09-11 14:53 UTCEPSS rescore
Show 8 more
  1. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-11 14:53 UTCEG score recompute
  3. 2026-09-11 14:53 UTCGHSA enrichment
  4. 2026-09-11 14:35 UTCEG score recompute
  5. 2026-09-11 14:35 UTCGHSA enrichment
  6. 2026-09-11 00:25 UTCEG score recompute
  7. 2026-09-10 23:25 UTCEG score recompute
  8. 2026-09-10 23:24 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-81906?
CVE-2026-81906 is a medium vulnerability published on September 10, 2026. Concrete CMS OAuth callback login path prior to version 9.5.3 did not check whether an account was active or email-validated before establishing a session. A deactivated or unvalidated user with an existing OAuth binding could complete authentication and receive a session that was fully…
When was CVE-2026-81906 disclosed?
CVE-2026-81906 was first published in the National Vulnerability Database on September 10, 2026, with the most recent update on September 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-81906 actively exploited?
CVE-2026-81906 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 67.6% of all scored CVEs.
What is the CVSS score of CVE-2026-81906?
CVE-2026-81906 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-81906?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81906, 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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