How severe is CVE-2020-21359?

CVE-2020-21359 has a CVSS 3.x base score of 9.8, 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 high.

Is CVE-2020-21359 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-21359?

CVE-2020-21359 affects Maccms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-21359?

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-2020-21359 published?

CVE-2020-21359 was published on 2021-08-11 and last updated on 2026-06-17.

CVE-2020-21359

CVE-2020-21359 is a critical-severity vulnerability in Maccms with a CVSS 3.x base score of 9.8. 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-434.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Maccms
Published: 2021-08-11
Last modified: 2026-06-17

Description

An arbitrary file upload vulnerability in the Template Upload function of Maccms10 allows attackers bypass the suffix whitelist verification to execute arbitrary code via adding a character to the end of the uploaded file's name.

Frequently asked questions

What is CVE-2020-21359?: An arbitrary file upload vulnerability in the Template Upload function of Maccms10 allows attackers bypass the suffix whitelist verification to execute arbitrary code via adding a character to the end of the uploaded file's name.
How severe is CVE-2020-21359?: CVE-2020-21359 has a CVSS 3.x base score of 9.8, 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 high.
Is CVE-2020-21359 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-21359?: CVE-2020-21359 affects Maccms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-21359?: 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-2020-21359 published?: CVE-2020-21359 was published on 2021-08-11 and last updated on 2026-06-17.

References

https://github.com/magicblack/maccms10/issues/80

Affected products (1)

cpe:2.3:a:maccms:maccms:10.0:*:*:*:*:*:*:*

More vulnerabilities in Maccms

CVE-2021-45786 — Critical (CVSS 9.8): In maccms v10, an attacker can log in through /index.php/user/login in the "col" and "openid" parameters to gain…
CVE-2017-17733 — Critical (CVSS 9.8): Maccms 8.x allows remote command execution via the wd parameter in an index.php?m=vod-search request.
CVE-2025-28091 — Critical (CVSS 9.1): maccms10 v2025.1000.4047 has a Server-Side Request Forgery (SSRF) vulnerability via Add Article.
CVE-2025-28090 — Critical (CVSS 9.1): maccms10 v2025.1000.4047 is vulnerable to Server-Side Request Forgery (SSRF) in the Collection Custom Interface feature.
CVE-2025-28089 — Critical (CVSS 9.1): maccms10 v2025.1000.4047 is vulnerable to Server-Side Request Forgery (SSRF) via the Scheduled Task function.
CVE-2022-47872 — High (CVSS 8.8): A Server-Side Request Forgery (SSRF) in maccms10 v2021.1000.2000 allows attackers to force the application to make…

All CVEs affecting Maccms →

Other CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities

CVE-2026-48283 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Unrestricted Upload of File with Dangerous Type…
CVE-2026-48276 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Unrestricted Upload of File with Dangerous Type…
CVE-2026-57700 — Critical (CVSS 10.0): Unrestricted Upload of File with Dangerous Type vulnerability in Daan.Dev OMGF Pro allows Using Malicious Files. This…
CVE-2025-69129 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in WordPress & WooCommerce Scraper Plugin, Import Data from Any Site <= 1.0.7…
CVE-2026-40772 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in GeekyBot <= 1.2.2 versions.
CVE-2026-40412 — Critical (CVSS 10.0): Unrestricted upload of file with dangerous type in Azure Orbital Spatio allows an unauthorized attacker to execute code…

Browse all CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities →