How severe is CVE-2021-28998?

CVE-2021-28998 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-28998 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28998?

CVE-2021-28998 affects Cmsmadesimple Cms Made Simple. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-28998?

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-2021-28998 published?

CVE-2021-28998 was published on 2023-05-08 and last updated on 2026-06-17.

CVE-2021-28998

CVE-2021-28998 is a high-severity vulnerability in Cmsmadesimple Cms Made Simple with a CVSS 3.x base score of 7.2. 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: High (CVSS 3.x base score 7.2)
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Cmsmadesimple Cms Made Simple
Published: 2023-05-08
Last modified: 2026-06-17

Description

File upload vulnerability in CMS Made Simple through 2.2.15 allows remote authenticated attackers to gain a webshell via a crafted phar file.

Frequently asked questions

What is CVE-2021-28998?: File upload vulnerability in CMS Made Simple through 2.2.15 allows remote authenticated attackers to gain a webshell via a crafted phar file.
How severe is CVE-2021-28998?: CVE-2021-28998 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-28998 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28998?: CVE-2021-28998 affects Cmsmadesimple Cms Made Simple. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-28998?: 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-2021-28998 published?: CVE-2021-28998 was published on 2023-05-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:cmsmadesimple:cms_made_simple:*:*:*:*:*:*:*:*

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

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