Vulnerability in Zammad

CVE-2026-34720

Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.1 and 6.5.4, the SSO mechanism in Zammad was not verifying the header originates from a trusted SSO proxy/gateway before applying further actions on it. This vulnerability is fixed in 7.0.1 and 6.5.4.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.001 (2.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 3rd percentile — 2.9% 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-2026-34720: held from 0.001 to 0.001.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: +0.000

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-2026-34720?
CVE-2026-34720 is a medium-severity vulnerability in Zammad, classified under Origin Validation Error. CVSS score: 4.3/10. Published 2026-04-08.
How severe is CVE-2026-34720?
Medium severity. CVSS v3 base score is 4.3 out of 10.