How severe is CVE-2020-26029?

CVE-2020-26029 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2020-26029 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-26029?

CVE-2020-26029 affects Zammad. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-26029?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-26029 published?

CVE-2020-26029 was published on 2020-12-28 and last updated on 2026-06-17.

CVE-2020-26029

CVE-2020-26029 is a medium-severity vulnerability in Zammad with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-863
Affected product: Zammad
Published: 2020-12-28
Last modified: 2026-06-17

Description

An issue was discovered in Zammad before 3.4.1. There are wrong authorization checks for impersonation requests via X-On-Behalf-Of. The authorization checks are performed for the actual user and not the one given in the X-On-Behalf-Of header.

Frequently asked questions

What is CVE-2020-26029?: An issue was discovered in Zammad before 3.4.1. There are wrong authorization checks for impersonation requests via X-On-Behalf-Of. The authorization checks are performed for the actual user and not the one given in the X-On-Behalf-Of header.
How severe is CVE-2020-26029?: CVE-2020-26029 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2020-26029 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-26029?: CVE-2020-26029 affects Zammad. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-26029?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-26029 published?: CVE-2020-26029 was published on 2020-12-28 and last updated on 2026-06-17.

References

https://zammad.com/news/security-advisory-zaa-2020-20

Affected products (1)

cpe:2.3:a:zammad:zammad:*:*:*:*:*:*:*:*

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