What is CVE-2023-28820?

CVE-2023-28820 is a low-severity vulnerability in Concretecms Concrete Cms, classified under Cross-site Scripting. CVSS score: 2.0/10. Published 2023-04-28.

How severe is CVE-2023-28820?

Low severity. CVSS v3 base score is 2.0 out of 10.

XSS in Concretecms Concrete Cms

CVE-2023-28820

Concrete CMS (previously concrete5) before 9.1 is vulnerable to stored XSS in RSS Displayer via the href attribute because the link element input was not sanitized.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2023-04-28 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 2.0 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.004 (31.0th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 31.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Concretecms Concrete Cms

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/concretecms/concretecms/releases (Release Notes)
www.concretecms.org/about/project-news/security/concrete-cms-security-advisory-… (Vendor Advisory)

Frequently asked questions

What is CVE-2023-28820?: CVE-2023-28820 is a low-severity vulnerability in Concretecms Concrete Cms, classified under Cross-site Scripting. CVSS score: 2.0/10. Published 2023-04-28.
How severe is CVE-2023-28820?: Low severity. CVSS v3 base score is 2.0 out of 10.