Vulnerability-Lookup

GHSA-2C5V-FHHF-MWQ5

Vulnerability from github – Published: 2026-09-11 00:31 – Updated: 2026-09-11 00:31

Details

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.

Severity

6.3 (Medium)


                  
                    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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-81906"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-288"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T00:19:48Z",
    "severity": "MODERATE"
  },
  "details": "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.\u00a0The 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.",
  "id": "GHSA-2c5v-fhhf-mwq5",
  "modified": "2026-09-11T00:31:16Z",
  "published": "2026-09-11T00:31:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-81906"
    },
    {
      "type": "WEB",
      "url": "https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-81906 (GCVE-0-2026-81906)

Vulnerability from cvelistv5 – Published: 2026-09-10 23:20 – Updated: 2026-09-11 14:27

Title

[UNREVIEWED] OAuth Callback Login Bypasses Deactivated-Account Checks

Summary

Severity

6.3 (Medium)


                        
                          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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-11 14:26 UTC

CWE

CWE-288 - Authentication bypass using an alternate path or channel

Assigner

ConcreteCMS CNA under the mitre root

CNA scorecard B 84/100 over 111 records in the last 180 days details

References

1 reference

URL	Tags
https://documentation.concretecms.org/developers/…	release-notes

Impacted products

1 product

Vendor	Product	Version
Concrete CMS	Concrete CMS	Affected: 5.0.0 , ≤ 9.5.2 (git)

Credits

tenzai

Show details on NVD website

JSON

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                "id": "CVE-2026-81906",
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                  },
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                  },
                  {
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                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-11T14:26:46.492008Z",
                "version": "2.0.3"
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      "metrics": [
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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