CVE-2020-26030

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-12-28 · updated 2026-06-17
Weakness: CWE-287

Description

An issue was discovered in Zammad before 3.4.1. There is an authentication bypass in the SSO endpoint via a crafted header, when SSO is not configured. An attacker can create a valid and authenticated session that can be used to perform any actions in the name of other users.

Affected products

zammad: from 1.0.0 before 3.4.1 — fixed in 3.4.1

How to fix

Upgrade to a fixed version: zammad 3.4.1. Check the vendor advisory for mitigations.

References

https://zammad.com/news/security-advisory-zaa-2020-18
https://zammad.com/news/security-advisory-zaa-2020-18

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