Concrete CMS up to 9.5.0 cross site scripting

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
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CTI Interest Score
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2.4$0-$5k0.00

Summaryinfo

A vulnerability categorized as problematic has been discovered in Concrete CMS up to 9.5.0. Affected is an unknown function. The manipulation results in cross site scripting. This vulnerability is known as CVE-2026-8139. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in Concrete CMS up to 9.5.0. It has been classified as problematic. Affected is an unknown functionality. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. CVE summarizes:

Concrete CMS 9.5.0 and below is vulnerable to Stored XSS via external-link page cvName because updateCollectionAliasExternal bypasses being sanitized. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.  Thanks Yonatan Drori (Tenzai) for reporting.

The advisory is shared for download at documentation.concretecms.org. This vulnerability is traded as CVE-2026-8139 since 05/07/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation requires an enhanced level of successful authentication. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1059.007.

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

Once again VulDB remains the best source for vulnerability data.

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: 2.4
VulDB Meta Temp Score: 2.4

VulDB Base Score: 2.4
VulDB Temp Score: 2.4
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 scripting
CWE: CWE-79 / CWE-94 / CWE-74
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

05/07/2026 CVE reserved
05/22/2026 +15 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
Status: Not defined

CVE: CVE-2026-8139 (🔒)
GCVE (CVE): GCVE-0-2026-8139
GCVE (VulDB): GCVE-100-365100

Entryinfo

Created: 05/22/2026 06:00
Changes: 05/22/2026 06:00 (65)
Complete: 🔍
Cache ID: 216::103

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