How severe is CVE-2021-38366?

CVE-2021-38366 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-38366 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-38366?

CVE-2021-38366 affects Sitecore. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-38366?

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-2021-38366 published?

CVE-2021-38366 was published on 2021-08-12 and last updated on 2026-06-17.

CVE-2021-38366

CVE-2021-38366 is a high-severity vulnerability in Sitecore with a CVSS 3.x base score of 8.8. 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: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 3% (85th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Sitecore
Published: 2021-08-12
Last modified: 2026-06-17

Description

Sitecore through 10.1, when Update Center is enabled, allows remote authenticated users to upload arbitrary files and achieve remote code execution by visiting an uploaded .aspx file at an admin/Packages URL.

Frequently asked questions

What is CVE-2021-38366?: Sitecore through 10.1, when Update Center is enabled, allows remote authenticated users to upload arbitrary files and achieve remote code execution by visiting an uploaded .aspx file at an admin/Packages URL.
How severe is CVE-2021-38366?: CVE-2021-38366 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-38366 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-38366?: CVE-2021-38366 affects Sitecore. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-38366?: 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-2021-38366 published?: CVE-2021-38366 was published on 2021-08-12 and last updated on 2026-06-17.

References

https://blog.istern.dk/2021/08/10/sitecore-10-authenticated-file-upload-to-rce/

Affected products (1)

cpe:2.3:a:sitecore:sitecore:*:*:*:*:*:*:*:*

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