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CVE-2021-37334

31
FAUCET Score

CVE-2021-37334 is a critical remote code execution and arbitrary file deletion vulnerability affecting Umbraco Forms versions 4.0.0 through 8.7.5. The flaw stems from improper file extension validation, allowing attackers to upload malicious files to a temporary directory and then overwrite the web.config file to execute arbitrary code. With a CVSS score of 9.8 (Critical), this vulnerability is easily exploitable over the network with low attack complexity, potentially leading to complete compromise of confidentiality, integrity, and availability. While no active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB) has been identified, and community discussion is minimal, the high FAUCET Risk Score of 80/100 indicates significant potential danger.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.0.0, < 4.4.9CPE matchmatch criteria
cpe:2.3:a:umbraco:forms:*:*:*:*:*:*:*:*
>= 6.0.0, < 6.0.10CPE matchmatch criteria
cpe:2.3:a:umbraco:forms:*:*:*:*:*:*:*:*
>= 7.0.0, < 7.0.7CPE matchmatch criteria
cpe:2.3:a:umbraco:forms:*:*:*:*:*:*:*:*
>= 7.1.0, < 7.1.4CPE matchmatch criteria
cpe:2.3:a:umbraco:forms:*:*:*:*:*:*:*:*
>= 7.2.0, < 7.2.1CPE matchmatch criteria
cpe:2.3:a:umbraco:forms:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.74%
Probability of exploitation in next 30 days
EPSS Percentile
84.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0274 is in the 75th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

umbraco.com / blog/security-advisory-20th-of-july-2021-patch-is-now-available
PatchVendor Advisory
umbraco.com / blog/security-advisory-security-patches-for-umbraco-forms-ready-on-july-20th-2021-at-7-am-utc
Vendor Advisory