CVE-2026-3241 json
Concrete CMS below version 9.4.8 is vulnerable to a stored cross-site scripting (XSS) in the "Legacy Form" block.
published 2026-03-04 8 mo ago modified 2026-06-17 4 mo ago also GHSA-f4vq-pj32-gr4q , EUVD-2026-9359
- cvss
- 4.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 14%
- public exploits
- 0
- none known
Summary
In Concrete CMS below version 9.4.8, a stored cross-site scripting (XSS) vulnerability exists in the "Legacy Form" block. An authenticated user with permissions to create or edit forms (e.g., a rogue administrator) can inject a persistent JavaScript payload into the options of a multiple-choice question (Checkbox List, Radio Buttons, or Select Box). This payload is then executed in the browser of any user who views the page containing the form. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 4.8 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks M3dium for reporting.
Patch / fix
- packagist concrete5/concrete5 9.4.8
- concretecms concrete_cms 9.4.8
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 8 mo ago
Exploit prediction
0.24% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/concretecms/concretecms/pull/12826 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 4.8 | CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N |
| CNA | 4.0 | 4.8 | CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/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 |
| NVD | 3.1 | 4.8 | CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N |
| GitHub | 3.1 | 4.8 | CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| packagist | concrete5/concrete5 | <9.4.8 |
9.4.8 |
Affected products
- Concrete CMS Concrete CMS
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/concretecms/concretecms/pull/12826
web, exploit, issue-tracking, vendor-advisory
-
documentation.concretecms.org
/9-x/developers/introduction/version-history/948-release-notes
web, patch, release-notes, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-3241
advisory
-
github.com
/concretecms/concretecms
package
Sources
- CVE List CVE-2026-3241
- GitHub Advisory GHSA-f4vq-pj32-gr4q
- NVD CVE-2026-3241
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