How severe is CVE-2021-42084?

CVE-2021-42084 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 none, integrity none, and availability high.

Is CVE-2021-42084 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42084?

CVE-2021-42084 affects Zammad. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42084?

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

When was CVE-2021-42084 published?

CVE-2021-42084 was published on 2021-10-07 and last updated on 2026-06-17.

CVE-2021-42084

CVE-2021-42084 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-835.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Zammad
Published: 2021-10-07
Last modified: 2026-06-17

Description

An issue was discovered in Zammad before 4.1.1. An attacker with valid agent credentials may send a series of crafted requests that cause an endless loop and thus cause denial of service.

Frequently asked questions

What is CVE-2021-42084?: An issue was discovered in Zammad before 4.1.1. An attacker with valid agent credentials may send a series of crafted requests that cause an endless loop and thus cause denial of service.
How severe is CVE-2021-42084?: CVE-2021-42084 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 none, integrity none, and availability high.
Is CVE-2021-42084 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42084?: CVE-2021-42084 affects Zammad. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42084?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-42084 published?: CVE-2021-42084 was published on 2021-10-07 and last updated on 2026-06-17.

References

https://zammad.com/en/advisories/zaa-2021-11

Affected products (1)

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

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