What is CVE-2021-42137?

CVE-2021-42137 is a medium-severity vulnerability in Zammad, classified under Incorrect Authorization. CVSS score: 5.3/10. Published 2021-10-11.

How severe is CVE-2021-42137?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Auth bypass in Zammad

CVE-2021-42137

An issue was discovered in Zammad before 5.0.1. In some cases, there is improper enforcement of the privilege requirement for viewing a list of tickets that shows title, state, etc.

Vulnerability class: Broken Access Control

Published 2021-10-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.008 (56.2th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 56.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Zammad

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

zammad.com/en/advisories/zaa-2021-19 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-42137?: CVE-2021-42137 is a medium-severity vulnerability in Zammad, classified under Incorrect Authorization. CVSS score: 5.3/10. Published 2021-10-11.
How severe is CVE-2021-42137?: Medium severity. CVSS v3 base score is 5.3 out of 10.