Using a specially formed request employing chunked transfer encoding, an attacker can cause a buffer overflow on the Web servers that will crash them, according to a separate security alert released by Sun.
This can allow an attacker to run malicious code, Sun said. Chunked transfer encoding is a feature allowing applications to maintain persistent connections without knowing the length of the expected content.
The vulnerability can be exploited remotely, meaning that an attacker who does not have physical access to the machine can launch an attack.
The flaws affect iPlanet Web server 4.1 and Sun One Web server 6.0, according to the alerts.
Sun has released both a work around and service packs that fix the problem. Links to the downloads and more information about the vulnerability, can be found at www.sun.com/service/support/software/iplanet/alerts/transferencodingalert-23july2002.html.
Another vulnerability involving chunked encoding was discovered in the Apache Web server in June.