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Nessus Version 4.2.1 Released

As always we are excited to announce a new release of the Nessus vulnerability scanner. This is a point release (moving from 4.2.0 to 4.2.1) and introduces changes to the scanning engine only. The GUI has not been updated in this release, however GUI changes will be implemented and released independently from a point release.


From a user perspective, the biggest changes in 4.2.1 are the two performance items that improve the speed of the GUI and lower the memory overhead when doing a scan. With regards to the GUI, interaction between the GUI and the database has been improved to better handle browsing reports with thousands of hosts or thousands of open ports per host. Memory consumption has been designed to take better advantage of the allotted memory used by Nessus. For example, in previous versions there was a 5 MB overhead per host being scanned. This meant that if max_hosts was set to 100, you'd "lose" 500 MB of memory. In Nessus 4.2.1 the memory overhead per host has been reduced to less than 500 KB, which allows the user to dramatically raise 'max_hosts'.

If you are scanning large networks (hundreds of thousands of hosts or more), please consider using the 64-bit versions of Nessus. The 64-bit platform running the Nessus server can address more than 4GB of memory, allowing Nessus to potentially scan more hosts in a shorter period of time.

There were several bug fixes included in the 4.2.1 release as well:

  • Fixed a memory leak when NASL was running with safe checks disabled
  • Fixed several segmentation faults that occurred when the system was low on resources
  • Improved performance on specific database queries that would take too much time to complete
  • Improved compatibility with HTTP proxies for the plugin updates
  • Fixed a bug that occurred when converting a large report to .nessus or .nessus.v1
  • Fixed a SQL error occurring when polling the scan progress while a filter is set for the report
  • Fixed a size limit for hosts tags
  • Fixed an issue that occurred when exporting data to a .nessus.v1 file, which would make the "Description" header sometimes go away
  • Fixed a bug in the"Avoid sequential scan" set option that resulted in only the first 256 IP address to be scanned
  • Fixed a bug in Nessus GUI that resulted in losing some host tags information in the report

New customers can download and evaluate Nessus for free by visiting the Nessus homepage. Existing customers can download the new version from the Tenable Support Portal. Detailed instructions and notes on upgrading are located in the Nessus 4.2 Installation Guide. Please contact Tenable Support ([email protected]) with any questions regarding the upgrade to Nessus 4.2.1.

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