Vulnerability in Umbraco Forms
CVE-2021-37334
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.027 (85.6th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 86th percentile — 85.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.027 · newest: 0.027 · change: 0.000
Affected products
References
- umbraco.com/blog/security-advisory-security-patches-for-umbraco-forms-ready-on-… (Vendor Advisory)
- umbraco.com/blog/security-advisory-20th-of-july-2021-patch-is-now-available/ (Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2021-37334?
- CVE-2021-37334 is a critical-severity vulnerability in Umbraco Forms. CVSS score: 9.8/10. Published 2021-08-25.
- How severe is CVE-2021-37334?
- Critical severity. CVSS v3 base score is 9.8 out of 10.