CVE-2026-81906

MEDIUMPre-NVD 6.36.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6% (49th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-75888 (ENISA EUVD) · GHSA-2c5v-fhhf-mwq5 (GitHub Security Advisories)Source: ENISA EUVD

6.3EG
EchelonGraph verdictMonitorNo fix is confirmed yet: check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 6.3Exploit: None knownExposed services: Not assessed

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

The CVE record's description, written by its CNA (Concrete CMS), states the affected versions: "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." No release containing a fix is confirmed on record.

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
6.3MEDIUMmedium confidence
EG Risk
44
EG Risk 44/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity63% × 45%
Impact severity (EG Severity): CVSS 6.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.6% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high.
EPSS PROB
0.6%
EPSS %ILE
49th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.3): severity, escalated by confirmed exploitation. This CVE's 6.3 is its impact severity (EG Severity), not escalated.

EG Severity
6.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

September 10, 2026

Last Modified

September 11, 2026

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 8× in last 7d / 56× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 126 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 26 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  2. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  3. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  4. 2026-10-30 01:55 UTCOSV refresh
  5. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  6. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  7. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  8. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  9. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  10. 2026-10-25 13:58 UTCEG score recompute
  11. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  12. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  13. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  14. 2026-10-22 13:46 UTCEG score recompute
  15. 2026-10-22 13:46 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  16. 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  17. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  18. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  19. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  20. 2026-10-18 03:08 UTCEG score recompute
  21. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  22. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  23. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  24. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  25. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
Show 75 more
  1. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  2. 2026-10-12 14:56 UTCEG score recompute
  3. 2026-10-11 19:20 UTCEG score recompute
  4. 2026-10-11 16:36 UTCEG score recompute
  5. 2026-10-11 13:54 UTCEG score recompute
  6. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  7. 2026-10-11 07:00 UTCEG score recompute
  8. 2026-10-11 07:00 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  9. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  10. 2026-10-10 08:05 UTCEG score recompute
  11. 2026-10-10 08:05 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  12. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  13. 2026-10-09 09:22 UTCEG score recompute
  14. 2026-10-09 09:22 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  15. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  16. 2026-10-08 11:06 UTCEG score recompute
  17. 2026-10-08 11:05 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  18. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  19. 2026-10-07 12:56 UTCEG score recompute
  20. 2026-10-07 12:56 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  21. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  22. 2026-10-06 14:36 UTCEG score recompute
  23. 2026-10-06 14:36 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  24. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  25. 2026-10-05 16:23 UTCEG score recompute
  26. 2026-10-05 16:23 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  27. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  28. 2026-10-04 17:28 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  29. 2026-10-03 19:20 UTCEG score recompute
  30. 2026-10-03 19:20 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  31. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  32. 2026-10-02 21:12 UTCEG score recompute
  33. 2026-10-02 21:12 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  34. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  35. 2026-10-01 22:55 UTCEG score recompute
  36. 2026-10-01 22:55 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  37. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  38. 2026-10-01 00:48 UTCEG score recompute
  39. 2026-10-01 00:48 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  40. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  41. 2026-09-30 02:41 UTCEG score recompute
  42. 2026-09-30 02:41 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  43. 2026-09-29 04:34 UTCEG score recompute
  44. 2026-09-29 04:34 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  45. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  46. 2026-09-28 06:26 UTCEG score recompute
  47. 2026-09-28 06:26 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  48. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  49. 2026-09-27 08:19 UTCEG score recompute
  50. 2026-09-27 08:19 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  51. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  52. 2026-09-26 10:11 UTCEG score recompute
  53. 2026-09-26 10:11 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  54. 2026-09-25 11:40 UTCEG score recompute
  55. 2026-09-25 11:40 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  56. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  57. 2026-09-24 13:30 UTCEG score recompute
  58. 2026-09-24 13:30 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  59. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  60. 2026-09-23 15:23 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  61. 2026-09-22 17:12 UTCEG score recompute
  62. 2026-09-22 17:12 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  63. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  64. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  65. 2026-09-21 18:53 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  66. 2026-09-20 20:46 UTCEG score recompute
  67. 2026-09-20 20:45 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  68. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  69. 2026-09-19 22:38 UTCEG score recompute
  70. 2026-09-19 22:38 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  71. 2026-09-19 00:31 UTCEG score recompute
  72. 2026-09-19 00:30 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5
  73. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  74. 2026-09-18 02:22 UTCEG score recompute
  75. 2026-09-18 02:22 UTCGHSA enrichmentGHSA-2c5v-fhhf-mwq5

Frequently asked(5)

What is CVE-2026-81906?
CVE-2026-81906 is a medium-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-81906 published?
The CVE record for CVE-2026-81906 was published on September 10, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 11, 2026; the record at its source may have been updated since.
Is CVE-2026-81906 actively exploited?
CVE-2026-81906 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (49th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-81906?
CVE-2026-81906 has a CVSS base score of 6.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-81906?
No fix for CVE-2026-81906 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The CVE record's description, written by its CNA (Concrete CMS), states the affected versions: "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." No release containing a fix is confirmed on record. The vendor advisories EchelonGraph has for CVE-2026-81906 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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