Concrete CMS up to 9.5.0 edit_file_contents cross-site request forgery

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.3$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in Concrete CMS up to 9.5.0. The affected element is the function edit_file_contents. Executing a manipulation can lead to cross-site request forgery. This vulnerability is handled as CVE-2026-8340. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability has been found in Concrete CMS up to 9.5.0 and classified as problematic. This vulnerability affects the function edit_file_contents. The manipulation with an unknown input leads to a cross-site request forgery vulnerability. The CWE definition for the vulnerability is CWE-352. The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request. As an impact it is known to affect integrity. CVE summarizes:

Concrete CMS 9.5.0 and below is vulnerable to CSRF via Backend\File::approveVersion. Victim with edit_file_contents permission is CSRF'd into publishing an attacker-chosen previously-uploaded version (downgrade to an older version of a file, or activation of a co-editor's unpublished version). The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

The weakness was released by Winston Crooker. The advisory is available at documentation.concretecms.org. This vulnerability was named CVE-2026-8340 since 05/11/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.3

VulDB Base Score: 4.3
VulDB Temp Score: 4.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross-site request forgery
CWE: CWE-352 / CWE-862 / CWE-863
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

05/11/2026 CVE reserved
05/22/2026 +11 days Advisory disclosed
05/22/2026 +0 days VulDB entry created
05/22/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: documentation.concretecms.org
Researcher: Winston Crooker
Status: Not defined

CVE: CVE-2026-8340 (🔒)
GCVE (CVE): GCVE-0-2026-8340
GCVE (VulDB): GCVE-100-365206

Entryinfo

Created: 05/22/2026 17:36
Changes: 05/22/2026 17:36 (67)
Complete: 🔍
Cache ID: 216::103

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