No exploitation reportedFix available

CVE-2020-26030

Q: Is CVE-2020-26030 actively exploited?

Active exploitation of CVE-2020-26030 has not been confirmed. Its EPSS score was 1.4% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2020-26030?

CVE-2020-26030 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2020-12-28
Fixed in3.4.1
WeaknessCWE-287

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2020-12-2808:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-26030?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-26030?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Zammad

Branch	Affected	Fixed in	Source
3.4	≥ 1.0.0, < 3.4.1	3.4.1	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Zammad to 3.4.1

Advisories and patches

zammad.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
NVDweakness (CWE)CWE-287read 2026-10-23
FIRST EPSSEPSS score1.4 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2020-12-28
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-26030?

Is CVE-2020-26030 actively exploited?

Active exploitation of CVE-2020-26030 has not been confirmed. Its EPSS score was 1.4% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-26030?

CVE-2020-26030 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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