CVE-2026-8337
📛 CVE Title
Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys when sites are running concurrent public surveys and private surveys
Description
Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys. To be vulnerable, a site would have to be configured in such a way that both public and private surveys are present on the site. An unauthenticated attacker can vote in the restricted survey by submitting the restricted optionID through the public survey’s endpoint. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 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 Zer0daySec https://github.com/Zee99y for reporting
Overview
- State
- PUBLISHED
- Assigner (CNA)
- ConcreteCMS
- CVSS severity
- MEDIUM
- CVSS score
- 6.3 / 10
- CVSS 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- Effective score
- 6.3 / 10 MEDIUM source: CNA overview
- CWE(s)
-
CWE-639,CWE-565 - Reserved
- 2026-05-11
- Published
- 2026-05-21 21:13 UTC
- Last updated
- 2026-05-22 13:13 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/8xxx/CVE-2026-8337.json
- Linked Threat
- CVE-2026-8337 — CVE-2026-8337
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- NVD published
- 2026-05-21 22:16:50 UTC
- NVD last modified
- 2026-05-21 22:16:50 UTC
- EPSS score
- 0.0005 (probability of exploitation in next 30 days)
- EPSS percentile
- 15.62% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24
NVD / KEV / EPSS data refreshed 2026-05-25 00:24 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2026-31359 - Assigner
- ConcreteCMS
- Published
- May 21, 2026, 9:13:07 PM
- Updated
- May 22, 2026, 1:13:57 PM
- EUVD base score (CVSS 4.0)
-
6.3 / 10
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 - EUVD-reported EPSS
- 0.0600
- Vendors
- Concrete CMS
- Products
-
Concrete CMS (5.0 ≤9.5.0)
- Aliases
-
GHSA-8c7c-h7px-267g
ENISA description: Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys. To be vulnerable, a site would have to be configured in such a way that both public and private surveys are present on the site. An unauthenticated attacker can vote in the restricted survey by submitting the restricted optionID through the public survey’s endpoint. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 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 Zer0daySec https://github.com/Zee99y for reporting
Affected products (1)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| Concrete CMS | Concrete CMS |
5.0 (affected)
|
— |
Vendor references (1)
References embedded in the original CVE record by the assigning CNA.
Web references (4)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
- https://www.first.org/epss/ tenable:www.first.org
- https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes tenable:documentation.concretecms.org
- https://nvd.nist.gov/vuln/detail/CVE-2026-8337 tenable:nvd.nist.gov
- https://www.cve.org/CVERecord?id=CVE-2026-8337 tenable:www.cve.org
NVD-tagged references (1)
Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.
- https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes ff5b8ace-8b95-4078-9743-eac1ca5451de
Remediations (17)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:app.opencve.io
Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys. To be vulnerable, a site would have to be configured in such a way that both public and private surveys are present on the site. An unauthenticated attacker can vote in the restricted survey by submitting the restricted optionID through the public survey's endpoint. The Concrete CMS security team gave this vulnerability a CVSS v ...
2026-05-24 12:02 UTC -
web:blog.talosintelligence.com
Microsoft has released its monthly security update for May 2026 , which includes 137 vulnerabilities affecting a range of products, including 16 that Microsoft marked as "critical".
2026-05-24 12:02 UTC -
web:community.ui.com
Published: May 21, 2026 Updated: May 22, 2026 Version: 1.1 Revision: 1.1 Summary 1 of 5 A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS devices to execute a Command Injection. Affected Products: UniFi OS Server (Version 5.0.6 and earlier) Mitigation : Update your UniFi OS Server to Version 5.0.8 or later ...
2026-05-24 12:02 UTC -
web:cybersecuritynews.com
Microsoft released its March 2026 Patch Tuesday security update on March 10, 2026 , addressing 78 vulnerabilities across Windows, Microsoft Office, Azure, SQL Server, and .NET. The update includes one actively exploited zero-day vulnerability and multiple Critical-rated flaws demanding immediate attention from security teams. The most urgent fix this month is CVE - 2026 -21262, the sole zero-day ...
2026-05-24 12:02 UTC -
web:nvd.nist.gov
Information Technology Laboratory National Vulnerability Database Vulnerabilities
2026-05-24 12:02 UTC -
web:portal.msrc.microsoft.com
The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.
2026-05-24 12:02 UTC -
web:techdocs.broadcom.com
What's New This release resolves CVE -2025-22224, CVE -2025-22225, and CVE -2025-22226. For more information on these vulnerabilities and their impact on Broadcom products, see VMSA-2025-0004.
2026-05-24 12:02 UTC -
web:www.oracle.com
This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.
2026-05-24 12:02 UTC -
web:www.thehackerwire.com
What is CVE-2026-8337 ? How do I fix or mitigate CVE-2026-8337 ? To protect against CVE-2026-8337 , you should: (1) Apply the latest security patches from the vendor, (2) Check official security advisories for specific remediation steps, (3) Update affected software to the latest version, and (4) Monitor your systems for any signs of exploitation.
2026-05-24 12:02 UTC -
web:zecurit.com
Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .
2026-05-24 12:02 UTC -
web:cisa.gov
Update (08/12/2025): CISA has updated this alert to provide clarification on identifying Exchange Servers on an organization's networks and provided further guidance on running the Microsoft Exchange Health Checker. Update (08/07/2025): CISA issued Emergency Directive (ED) 25-02: Mitigate Microsoft Exchange Vulnerability in response to CVE -2025-53786
2026-05-26 03:00 UTC -
web:cybersecuritynews.com
Microsoft Exchange Server spoofing flaw, is being actively exploited against on-premises systems before a permanent patch is available.
2026-05-26 03:00 UTC -
web:guide.sonatype.com
Technical security analysis for CVE-2026-8337 . CVSS 6.3 severity. View CVSS vectors, CWE classifications, and exploit maturity ratings.
2026-05-26 03:00 UTC -
web:techcommunity.microsoft.com
We wanted to tell you how to address the Exchange Server May 2026 vulnerability CVE - 2026 -42897.
2026-05-26 03:00 UTC -
web:vulmon.com
Vulnerability Summary Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys. To be vulnerable, a site would have to be configured in such a way that both public and private surveys are present on the site. An unauthenticated attacker can vote in the restricted survey by submitting the restricted optionID through the public survey's endpoint. The Concrete CMS security team gave this ...
2026-05-26 03:00 UTC -
web:www.forbes.com
Updated May 18: This article has been updated to include further details on the emergency mitigation process recommended by Microsoft after the CVE - 2026 -42897 Exchange Server zero-day was ...
2026-05-26 03:00 UTC -
web:www.ninjaone.com
Catalog of Microsoft KB updates with insights on performance & user sentiment. Find out what's working, what's not, & make informed decisions.
2026-05-26 03:00 UTC
AI Forensic Analysis
Only Available for Registered Users. Sign in to view.
Raw JSON
The full cvelistV5 record. Download as CVE-2026-8337.json.
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-8337",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-22T13:13:50.327710Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-22T13:13:57.212Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://github.com/concretecms/concretecms",
"defaultStatus": "unaffected",
"product": "Concrete CMS",
"repo": "https://github.com/concretecms/concretecms",
"vendor": "Concrete CMS",
"versions": [
{
"lessThanOrEqual": "9.5.0",
"status": "affected",
"version": "5.0",
"versionType": "git"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Zer0daySec (GitHub: https://github.com/Zee99y)"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "<div>Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys. <span>To be vulnerable, a</span><span> site would have to be configured in such a way that both public and private surveys are present on the site. An </span><span>unauthenticated attacker can vote in the restricted survey by submitting the restricted </span><code>optionID</code><span> through the public survey\u2019s endpoint. </span><span>The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of</span><span> 6.3 with vector </span><span>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 </span><span><a href=\"https://github.com/Zee99y\">Zer0daySec</a> for reporting</span></div>"
}
],
"value": "Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys.\u00a0To be vulnerable, a\u00a0site would have to be configured in such a way that both public and private surveys are present on the site. An\u00a0unauthenticated attacker can vote in the restricted survey by submitting the restricted optionID through the public survey\u2019s endpoint.\u00a0The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u00a06.3 with vector\u00a0CVSS: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\u00a0 Zer0daySec https://github.com/Zee99y \u00a0for reporting"
}
],
"impacts": [
{
"capecId": "CAPEC-31",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-31 Accessing/Intercepting/Modifying HTTP Cookies"
}
]
},
{
"capecId": "CAPEC-1",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-1 Accessing Functionality Not Properly Constrained by ACLs"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"baseScore": 6.3,
"baseSeverity": "MEDIUM",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "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",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-639",
"description": "CWE-639 Authorization bypass through User-Controlled key",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-565",
"description": "CWE-565 Reliance on cookies without validation and integrity checking",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-21T21:13:07.640Z",
"orgId": "ff5b8ace-8b95-4078-9743-eac1ca5451de",
"shortName": "ConcreteCMS"
},
"references": [
{
"tags": [
"release-notes"
],
"url": "https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes"
}
],
"source": {
"advisory": "https://hackerone.com/reports/3647015",
"defect": [
"HackerOne"
],
"discovery": "EXTERNAL"
},
"title": "Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys when sites are running concurrent public surveys and private surveys",
"x_generator": {
"engine": "Vulnogram 1.0.2"
}
}
},
"cveMetadata": {
"assignerOrgId": "ff5b8ace-8b95-4078-9743-eac1ca5451de",
"assignerShortName": "ConcreteCMS",
"cveId": "CVE-2026-8337",
"datePublished": "2026-05-21T21:13:07.640Z",
"dateReserved": "2026-05-11T15:59:55.797Z",
"dateUpdated": "2026-05-22T13:13:57.212Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}