Our Java Fuzzer Jazzer has found more than 19 Bugs (CVE-2021-37714) in the open-source library of jsoup. Eight of them might have a critical impact on the availability of web applications using jsoup. Users should update to jsoup 1.14.2 quickly, to avoid downtime!
Click to read the full bug report.
Jsoup is a popular Java library designed to parse, extract, and manipulate data stored in HTML documents. In addition, it can also be used to parse and build XML documents.
Applications that use jsoup to parse untrusted HTML or XML may be vulnerable to Denial of Service attacks. If the parser is run on user supplied input, an attacker may supply content that causes the parser to get stuck (loop indefinitely until cancelled), to complete more slowly than usual, or to throw an unexpected exception.
Example Stack Overflow (see Gist)
My team and I used our coverage-guided, in-process fuzzer for the JVM (Jazzer), to fuzz the application. Jazzer is extremely useful to find bugs in fuzz targets that parse complex and nested structures such as HTML, XML or JSON.