XSS in Zammad

CVE-2026-34718

Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.1 and 6.5.4, the HTML sanitizer for ticket articles was missing proper sanitization of data: ... URI schemes, resulting in storing such malicious content in the database of the Zammad instance. The Zammad GUI is rendering this content, due to applied CSP rules no harm was done by e.g., clicking such a link. This vulnerability is fixed in 7.0.1 and 6.5.4.

Published · last modified .

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: 0.003 (15.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-34718: held from 0.001 to 0.003.

EPSS over last 30 days · oldest: 0.001 · newest: 0.003 · change: +0.001

Affected products

  • Zammad — versions < 6.5.4, 7.0.0, >= 7.0.0-alpha, < 7.0.1

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-34718?
CVE-2026-34718 is a medium-severity vulnerability in Zammad, classified under Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS). CVSS score: 6.1/10. Published 2026-04-08.
How severe is CVE-2026-34718?
Medium severity. CVSS v3 base score is 6.1 out of 10.