What is CVE-2026-8139?

CVE-2026-8139 is a medium-severity vulnerability in Concrete Cms, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-05-21.

How severe is CVE-2026-8139?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Concrete Cms

CVE-2026-8139

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 ve…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.000 (6.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

Affected products

Concrete Cms — versions 5.0
Concretecms Concrete_cms

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

ff5b8ace-8b95-4078-9743-eac1ca5451de (release-notes, Vendor Advisory)

Frequently asked questions

What is CVE-2026-8139?: CVE-2026-8139 is a medium-severity vulnerability in Concrete Cms, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-05-21.
How severe is CVE-2026-8139?: Medium severity. CVSS v3 base score is 5.4 out of 10.