How severe is CVE-2020-10101?

CVE-2020-10101 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-10101 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-10101?

CVE-2020-10101 affects Zammad. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-10101?

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

When was CVE-2020-10101 published?

CVE-2020-10101 was published on 2020-03-05 and last updated on 2026-06-17.

CVE-2020-10101

CVE-2020-10101 is a high-severity vulnerability in Zammad with a CVSS 3.x base score of 7.5. 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-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Zammad
Published: 2020-03-05
Last modified: 2026-06-17

Description

An issue was discovered in Zammad 3.0 through 3.2. The WebSocket server crashes when messages in non-JSON format are sent by an attacker. The message format is not properly checked and parsing errors not handled. This leads to a crash of the service process.

Frequently asked questions

What is CVE-2020-10101?: An issue was discovered in Zammad 3.0 through 3.2. The WebSocket server crashes when messages in non-JSON format are sent by an attacker. The message format is not properly checked and parsing errors not handled. This leads to a crash of the service process.
How severe is CVE-2020-10101?: CVE-2020-10101 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-10101 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-10101?: CVE-2020-10101 affects Zammad. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-10101?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-10101 published?: CVE-2020-10101 was published on 2020-03-05 and last updated on 2026-06-17.

References

https://zammad.com/news/security-advisory-zaa-2020-06

Affected products (1)

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

More vulnerabilities in Zammad

CVE-2022-48021 — Critical (CVSS 9.8): A vulnerability in Zammad v5.3.0 allows attackers to execute arbitrary code or escalate privileges via a crafted…
CVE-2022-35490 — Critical (CVSS 9.8): Zammad 5.2.0 is vulnerable to privilege escalation. Zammad has a prevention against brute-force attacks trying to guess…
CVE-2021-42090 — Critical (CVSS 9.8): An issue was discovered in Zammad before 4.1.1. The Form functionality allows remote code execution because…
CVE-2021-42094 — Critical (CVSS 9.8): An issue was discovered in Zammad before 4.1.1. Command Injection can occur via custom Packages.
CVE-2020-26030 — Critical (CVSS 9.8): An issue was discovered in Zammad before 3.4.1. There is an authentication bypass in the SSO endpoint via a crafted…
CVE-2017-6080 — Critical (CVSS 9.8): An issue was discovered in Zammad before 1.0.4, 1.1.x before 1.1.3, and 1.2.x before 1.2.1, caused by lack of a…

All CVEs affecting Zammad →

Other CWE-20 (Improper Input Validation) vulnerabilities

CVE-2026-48316 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48281 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48277 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48055 — Critical (CVSS 10.0): Streambert is a cross-platform Electron Desktop App to stream and download any video media. In versions 2.4.0 and…
CVE-2026-34910 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi OS…
CVE-2026-33587 — Critical (CVSS 10.0): Lack of user input sanitisation in Open Notebook v1.8.3 allows the application user to execute Python code (and…

Browse all CWE-20 (Improper Input Validation) vulnerabilities →