Vendor: SonicWall
Vendor URL:
Versions affected:,
Systems Affected: SMA 100 Series (SMA 200, 210, 400, 410, 500v)
Author: Richard Warren 
Risk: CVSS 8.2 (High)


SonicWall SMA 100 Series appliances running firmware versions, and below suffer from a Stored Cross-Site Scripting (XSS) vulnerability within the management interface. This vulnerability arises due to lack of sufficient output encoding when displaying postscript file names within the management interface.

Due to CVE-2021-20040, this issue can be exploited by a remote, unauthenticated attacker.


When combined with CVE-2021-20040, this vulnerability may allow a remote unauthenticated attacker to inject arbitrary JavaScript into a page within the management interface. When an authenticated administrator visits this page within the management interface, arbitrary JavaScript could be executed within the administrators authenticated session.

An attacker with access to an administrative session could later exploit CVE-2021-20044 to achieve Remote Code Execution.


Upgrade to SMA version, or above.

Vendor Communication

2021-10-29 - Vulnerability reported to SonicWall PSIRT.
2021-11-02 - Reply from SonicWall PSIRT stating that the vulnerability has been "rejected" as a duplicate/known issue.
2021-11-06 - SonicWall confirm they have addressed the other reported issues and shared a draft KB article, which omits details of arbitrary file-deletion and XSS issues. NCC Group requests clarification around this - providing evidence of successful exploitation on latest firmware versions ( and
2021-11-06 - SonicWall PSIRT respond stating that these issues were rejected, referencing the original triage response.
2021-12-07 - Patch released and SonicWall publish KB article.
2021-12-07 - NCC Group request further clarification on missing vulnerabilities.
2021-12-08 - NCC Group confirms that the arbitrary file-deletion vulnerability was fixed on firmware versions and
2021-12-08 - SonicWall PSIRT responds stating that the issue was found by internal review prior to NCC Group's report, and for this reason was omitted from the advisory notes.
2021-12-09 - NCC Group advisory released.

Thanks to

Jennifer Fernick and Aaron Haymore from NCC Group for their assistance with disclosure.

About NCC Group

NCC Group is a global expert in cybersecurity and risk mitigation, working with businesses to protect their brand, value and reputation against the ever-evolving threat landscape. With our knowledge, experience and global footprint, we are best placed to help businesses identify, assess, mitigate & respond to the risks they face. We are passionate about making the Internet safer and revolutionizing the way in which organizations think about cybersecurity.

Published Date: 2021-12-09

Written By: Richard Warren