How severe is CVE-2020-26034?

CVE-2020-26034 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2020-26034 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-26034?

CVE-2020-26034 affects Zammad. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-26034?

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

When was CVE-2020-26034 published?

CVE-2020-26034 was published on 2020-12-28 and last updated on 2026-06-17.

CVE-2020-26034

CVE-2020-26034 is a medium-severity vulnerability in Zammad with a CVSS 3.x base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 4.0
EPSS exploit prediction: 1% (49th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Zammad
Published: 2020-12-28
Last modified: 2026-06-17

Description

An account-enumeration issue was discovered in Zammad before 3.4.1. The Create User functionality is implemented in a way that would enable an anonymous user to guess valid user email addresses. The application responds differently depending on whether the input supplied was recognized as associated with a valid user.

Frequently asked questions

What is CVE-2020-26034?: An account-enumeration issue was discovered in Zammad before 3.4.1. The Create User functionality is implemented in a way that would enable an anonymous user to guess valid user email addresses. The application responds differently depending on whether the input supplied was recognized as associated with a valid user.
How severe is CVE-2020-26034?: CVE-2020-26034 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2020-26034 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-26034?: CVE-2020-26034 affects Zammad. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-26034?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-26034 published?: CVE-2020-26034 was published on 2020-12-28 and last updated on 2026-06-17.

References

https://zammad.com/news/security-advisory-zaa-2020-14

Affected products (1)

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

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