Is CVE-2021-37334 actively exploited?

No active exploitation of CVE-2021-37334 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-37334 be exploited remotely?

Yes. CVE-2021-37334 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-37334?

CVE-2021-37334 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2021-37334

NVD-CWE-noinfoPublished: August 25, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official Description

Umbraco Forms version 4.0.0 up to and including 8.7.5 and below are vulnerable to a security flaw that could lead to a remote code execution attack and/or arbitrary file deletion. A vulnerability occurs because validation of the file extension is performed after the file has been stored in a temporary directory. By default, files are stored within the application directory structure at %BASEDIR%/APP_DATA/TEMP/FileUploads/. Whilst access to this directory is restricted by the root web.config file, it is possible to override this restriction by uploading another specially crafted web.config file to the temporary directory. It is possible to exploit this flaw to upload a malicious script file to execute arbitrary code and system commands on the server.

NVD Source

Technical Analysis

CVE-2021-37334 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.