Concrete CMS version 9 before 9.2.8 and previous versions before 8.5.16 are vulnerable to Stored XSS in the Custom Class page

published 2024-04-03 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-1295 , GHSA-r7q4-cw9r-vhp4

cvss: 3.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 29%
public exploits: 0; none known

Concrete CMS version 9 before 9.2.8 and previous versions before 8.5.16 are vulnerable to Stored XSS in the Custom Class page editing. Prior to the fix, a rogue administrator could insert malicious code in the custom class field due to insufficient validation of administrator provided data. The Concrete CMS security team gave this vulnerability a CVSS v3.1 score of 3.1 with a vector of AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:L https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator . Thanks Alexey Solovyev for reporting.

Patch / fix

fixed in 2 links 4

packagist concrete5/concrete5 8.5.16, 9.2.8
concretecms concrete_cms 8.5.16, 9.2.8

github.com/concretecms/concretecms@822e689 commit
github.com/concretecms/concretecms@f2ea49b commit
github.com/concretecms/concretecms#11988 pull request
github.com/concretecms/concretecms#11989 pull request

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-04-03)

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	3.1	CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:L
GitHub	3.1	3.1	CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:L
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	>=9.0.0RC1, <9.2.8 <8.5.16	9.2.8 8.5.16

Affected products

Concrete CMS Concrete CMS

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation
CWE-20 Improper Input Validation

References

Sources

CVE List CVE-2024-3179
GitHub Advisory GHSA-r7q4-cw9r-vhp4
NVD CVE-2024-3179

Fencer Vulns 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary