What is CVE-2018-5478?

CVE-2018-5478 is a medium-severity vulnerability in Contao, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2023-09-21.

How severe is CVE-2018-5478?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Contao

CVE-2018-5478

Contao 3.x before 3.5.32 allows XSS via the unsubscribe module in the frontend newsletter extension.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2023-09-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.004 (33.2th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 33.2% 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

Contao

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/FriendsOfPHP/security-advisories/blob/master/contao/core/CVE-2018-54… (Third Party Advisory)
security.snyk.io/vuln/SNYK-PHP-CONTAOCORE-70397 (Third Party Advisory)

Frequently asked questions

What is CVE-2018-5478?: CVE-2018-5478 is a medium-severity vulnerability in Contao, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2023-09-21.
How severe is CVE-2018-5478?: Medium severity. CVSS v3 base score is 6.1 out of 10.