How severe is CVE-2021-42091?

CVE-2021-42091 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-42091 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42091?

CVE-2021-42091 affects Zammad. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42091?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-42091 published?

CVE-2021-42091 was published on 2021-10-07 and last updated on 2026-06-17.

CVE-2021-42091

CVE-2021-42091 is a critical-severity vulnerability in Zammad with a CVSS 3.x base score of 9.1. 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-918.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v2: 6.4
EPSS exploit prediction: 1% (60th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-918
Affected product: Zammad
Published: 2021-10-07
Last modified: 2026-06-17

Description

An issue was discovered in Zammad before 4.1.1. SSRF can occur via GitHub or GitLab integration.

Frequently asked questions

What is CVE-2021-42091?: An issue was discovered in Zammad before 4.1.1. SSRF can occur via GitHub or GitLab integration.
How severe is CVE-2021-42091?: CVE-2021-42091 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-42091 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42091?: CVE-2021-42091 affects Zammad. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42091?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-42091 published?: CVE-2021-42091 was published on 2021-10-07 and last updated on 2026-06-17.

References

https://zammad.com/en/advisories/zaa-2021-08

Affected products (1)

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

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