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Vulnerability record · CVE-2020-26030 · published 28 December 2020

CVE-2020-26030: Zammad improper authentication vulnerability

Zammad · Zammad

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.

9.8 CVSS 3.1 Critical EPSS 1.4% · top 29.6% CWE-287 · Improper authentication
9.8CVSS 3.1 base score, v2 7.5
1.4%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2022-48021Zammad vulnerabilityA vulnerability in Zammad v5.3.0 allows attackers to execute arbitrary code or escalate privileges via a crafted message sent to the server.EPSS 0.88%9.8CVE-2022-35490Zammad improper restriction of authentication attempts vulnerabilityZammad 5.2.0 is vulnerable to privilege escalation. Zammad has a prevention against brute-force attacks trying to guess login credentials. After a co…EPSS 0.87%9.8CVE-2021-42090Zammad deserialization of untrusted data vulnerabilityAn issue was discovered in Zammad before 4.1.1. The Form functionality allows remote code execution because deserialization is mishandled.EPSS 2.3%9.8CVE-2021-42094Zammad command injection vulnerabilityAn issue was discovered in Zammad before 4.1.1. Command Injection can occur via custom Packages.EPSS 1.9%9.8CVE-2017-5619Zammad improper authentication vulnerabilityAn issue was discovered in Zammad before 1.0.4, 1.1.x before 1.1.3, and 1.2.x before 1.2.1. Attackers can login with the hashed password itself (e.g.…EPSS 1.5%9.8CVE-2017-6080Zammad cross-site request forgery vulnerabilityAn issue was discovered in Zammad before 1.0.4, 1.1.x before 1.1.3, and 1.2.x before 1.2.1, caused by lack of a protection mechanism involving HTTP A…EPSS 0.73%9.1CVE-2024-33668Zammad insecure direct object reference vulnerabilityAn issue was discovered in Zammad before 6.3.0. The Zammad Upload Cache uses insecure, partially guessable FormIDs to identify content. An attacker c…EPSS 0.45%9.1CVE-2022-27332Zammad missing authentication for critical function vulnerabilityAn access control issue in Zammad v5.0.3 allows attackers to write entries to the CTI caller log without authentication. This vulnerability can allow…EPSS 1.1%

Source: NIST National Vulnerability Database (record CVE-2020-26030), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.