CVE-2026-7886 (GCVE-0-2026-7886)
Vulnerability from cvelistv5 – Published: 2026-05-21 21:18 – Updated: 2026-05-22 13:12
VLAI
EPSS
VEX
Title
Concrete CMS 9.5.0 and below is vulnerable to IDOR in AddMessage/UpdateMessage via attachments[] parameter
Summary
Concrete CMS 9.5.0 and below is vulnerable to IDOR in AddMessage/UpdateMessage via attachments[] parameter which can lead to file permission bypass. The `AddMessage` and `UpdateMessage` conversation controllers accept user-supplied file attachment IDs and load files directly via `$em->find(File::class, $attachmentID)` without checking per-file permissions (`canViewFile()`). A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with a vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Tristan Mandani for reporting. if a site truly has private files, the owner should set up a private storage location https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations outside of the webroot so that permissions can be checked on view as well. That way, even if a authorized user attaches a file, or otherwise links to it, unauthorized users won't be able to view the file.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-22 13:11 UTC
CWE
- CWE-639 - Authorization bypass through User-Controlled key
Assigner
ConcreteCMS
CNA
References
1 reference
| URL | Tags |
|---|---|
| https://documentation.concretecms.org/9-x/develop… | release-notes |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Concrete CMS | Concrete CMS |
Affected:
5.0 , ≤ 9.5.0
(git)
|
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-7886",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-22T13:11:53.038446Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-22T13:12:00.371Z",
"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": "Tristan Mandani"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "Concrete CMS 9.5.0 and below is vulnerable to\u0026nbsp;IDOR in AddMessage/UpdateMessage via attachments[] parameter which can lead to file permission bypass.\u0026nbsp;The `AddMessage` and `UpdateMessage` conversation controllers accept user-supplied file attachment IDs and load files directly via `$em-\u0026gt;find(File::class, $attachmentID)` without checking per-file permissions (`canViewFile()`). A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.\u0026nbsp; The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u0026nbsp;2.3 with a vector\u0026nbsp;CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.\u0026nbsp;\u003cspan\u003eThanks Tristan Mandani for reporting.\u0026nbsp;\u003c/span\u003e\u003cdiv\u003e\u003cem\u003eif a site truly has private files, the owner should set up a \u003c/em\u003e\u003ca title=\"https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations\" href=\"https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations\"\u003e\u003cem\u003eprivate storage location\u003c/em\u003e\u003c/a\u003e\u003cem\u003e outside of the webroot so that permissions can be checked on view as well. That way, even if a authorized user attaches a file, or otherwise links to it, unauthorized users won\u0027t be able to view the file.\u003c/em\u003e\u003cbr\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv\u003e\u003cdiv\u003e\u003c/div\u003e\u003c/div\u003e\u003cbr\u003e\u003c/div\u003e"
}
],
"value": "Concrete CMS 9.5.0 and below is vulnerable to\u00a0IDOR in AddMessage/UpdateMessage via attachments[] parameter which can lead to file permission bypass.\u00a0The `AddMessage` and `UpdateMessage` conversation controllers accept user-supplied file attachment IDs and load files directly via `$em-\u003efind(File::class, $attachmentID)` without checking per-file permissions (`canViewFile()`). A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.\u00a0 The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u00a02.3 with a vector\u00a0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.\u00a0Thanks Tristan Mandani for reporting.\u00a0if a site truly has private files, the owner should set up a private storage location https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations outside of the webroot so that permissions can be checked on view as well. That way, even if a authorized user attaches a file, or otherwise links to it, unauthorized users won\u0027t be able to view the file."
}
],
"impacts": [
{
"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": 2.3,
"baseSeverity": "LOW",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "LOW",
"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:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "LOW",
"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"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-21T21:18:39.754Z",
"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/3626635",
"defect": [
"HackerOne"
],
"discovery": "EXTERNAL"
},
"title": "Concrete CMS 9.5.0 and below is vulnerable to IDOR in AddMessage/UpdateMessage via attachments[] parameter",
"x_generator": {
"engine": "Vulnogram 1.0.2"
}
}
},
"cveMetadata": {
"assignerOrgId": "ff5b8ace-8b95-4078-9743-eac1ca5451de",
"assignerShortName": "ConcreteCMS",
"cveId": "CVE-2026-7886",
"datePublished": "2026-05-21T21:18:39.754Z",
"dateReserved": "2026-05-05T19:31:00.289Z",
"dateUpdated": "2026-05-22T13:12:00.371Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-7886",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-22T13:11:53.038446Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-22T13:11:56.575Z",
"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": "Tristan Mandani"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "Concrete CMS 9.5.0 and below is vulnerable to\u0026nbsp;IDOR in AddMessage/UpdateMessage via attachments[] parameter which can lead to file permission bypass.\u0026nbsp;The `AddMessage` and `UpdateMessage` conversation controllers accept user-supplied file attachment IDs and load files directly via `$em-\u0026gt;find(File::class, $attachmentID)` without checking per-file permissions (`canViewFile()`). A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.\u0026nbsp; The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u0026nbsp;2.3 with a vector\u0026nbsp;CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.\u0026nbsp;\u003cspan\u003eThanks Tristan Mandani for reporting.\u0026nbsp;\u003c/span\u003e\u003cdiv\u003e\u003cem\u003eif a site truly has private files, the owner should set up a \u003c/em\u003e\u003ca title=\"https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations\" href=\"https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations\"\u003e\u003cem\u003eprivate storage location\u003c/em\u003e\u003c/a\u003e\u003cem\u003e outside of the webroot so that permissions can be checked on view as well. That way, even if a authorized user attaches a file, or otherwise links to it, unauthorized users won\u0027t be able to view the file.\u003c/em\u003e\u003cbr\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv\u003e\u003cdiv\u003e\u003c/div\u003e\u003c/div\u003e\u003cbr\u003e\u003c/div\u003e"
}
],
"value": "Concrete CMS 9.5.0 and below is vulnerable to\u00a0IDOR in AddMessage/UpdateMessage via attachments[] parameter which can lead to file permission bypass.\u00a0The `AddMessage` and `UpdateMessage` conversation controllers accept user-supplied file attachment IDs and load files directly via `$em-\u003efind(File::class, $attachmentID)` without checking per-file permissions (`canViewFile()`). A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.\u00a0 The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u00a02.3 with a vector\u00a0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.\u00a0Thanks Tristan Mandani for reporting.\u00a0if a site truly has private files, the owner should set up a private storage location https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations outside of the webroot so that permissions can be checked on view as well. That way, even if a authorized user attaches a file, or otherwise links to it, unauthorized users won\u0027t be able to view the file."
}
],
"impacts": [
{
"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": 2.3,
"baseSeverity": "LOW",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "LOW",
"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:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "LOW",
"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"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-21T21:18:39.754Z",
"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/3626635",
"defect": [
"HackerOne"
],
"discovery": "EXTERNAL"
},
"title": "Concrete CMS 9.5.0 and below is vulnerable to IDOR in AddMessage/UpdateMessage via attachments[] parameter",
"x_generator": {
"engine": "Vulnogram 1.0.2"
}
}
},
"cveMetadata": {
"assignerOrgId": "ff5b8ace-8b95-4078-9743-eac1ca5451de",
"assignerShortName": "ConcreteCMS",
"cveId": "CVE-2026-7886",
"datePublished": "2026-05-21T21:18:39.754Z",
"dateReserved": "2026-05-05T19:31:00.289Z",
"dateUpdated": "2026-05-22T13:12:00.371Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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
Loading timeline…
Loading…
Loading…
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.
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.
Loading…
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.