CVE-2026-3240 json
Concrete CMS below 9.4.8 is vulnerable to Stored XSS via Legacy form
published 8mo ago modified 4mo ago also GHSA-45fj-fvmm-xcc5 , EUVD-2026-9358
- 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 15%
- public exploits
- 0
- none known
Summary
In Concrete CMS below version 9.4.8, a user with permission to edit a page with element Legacy form can perform a stored XSS attack towards high-privilege accounts via the Question field. 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 minhnn42, namdi and quanlna2 from VCSLab-Viettel Cyber Security for reporting.
Patch / fix
- packagist concrete5/concrete5 9.4.8
- concretecms concrete_cms 9.4.8
Is CVE-2026-3240 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 8mo ago
Exploit prediction
0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-09).
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 |
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-2026-3240
advisory
-
github.com
/concretecms/concretecms
package
Sources
- CVE List CVE-2026-3240
- GitHub Advisory GHSA-45fj-fvmm-xcc5
- NVD CVE-2026-3240
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.