How severe is CVE-2021-42654?

CVE-2021-42654 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-2021-42654 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42654?

CVE-2021-42654 affects Sscms Siteserver Cms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42654?

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-2021-42654 published?

CVE-2021-42654 was published on 2022-05-24 and last updated on 2026-06-17.

CVE-2021-42654

Q: What is CVE-2021-42654?

SiteServer CMS < V5.1 is affected by an unrestricted upload of a file with dangerous type (getshell), which could be used to execute arbitrary code.

CVE-2021-42654 is a critical-severity vulnerability in Sscms Siteserver Cms 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% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Sscms Siteserver Cms
Published: 2022-05-24
Last modified: 2026-06-17

Description

SiteServer CMS < V5.1 is affected by an unrestricted upload of a file with dangerous type (getshell), which could be used to execute arbitrary code.

Frequently asked questions

What is CVE-2021-42654?: SiteServer CMS < V5.1 is affected by an unrestricted upload of a file with dangerous type (getshell), which could be used to execute arbitrary code.
How severe is CVE-2021-42654?: CVE-2021-42654 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-2021-42654 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42654?: CVE-2021-42654 affects Sscms Siteserver Cms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42654?: 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-2021-42654 published?: CVE-2021-42654 was published on 2022-05-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:sscms:siteserver_cms:*:*:*:*:*:*:*:*

More vulnerabilities in Sscms Siteserver Cms

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CVE-2022-28118 — Critical (CVSS 9.8): SiteServer CMS v7.x allows attackers to execute arbitrary code via a crafted plug-in.
CVE-2021-42655 — High (CVSS 8.8): SiteServer CMS V6.15.51 is affected by a SQL injection vulnerability.
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