Unserialization vulnerability in Relevanssi Premium could allow admins to execute arbitrary code (in some circumstances)


Last revised:

If logged in as an admin on any site you can go to settings, Relevanssi Premium, import or export options. This is a text field that accepts a serialised PHP object. It is possible to submit a string that contains an evil encoded object that executes arbitrary code (if there are classes available with particular methods such as __destruct).

Current state: Fixed

CVSS Summary

CVSS base scores for this vulnerability
Score 9 High
Vector Network
Complexity Low
Authentication Single
Confidentiality Complete
Integrity Complete
Availability Complete
You can read more about CVSS base scores on Wikipedia or in the CVSS specification.

Proof of concept

Achieving arbitrary code execution depends on which classes are available (i.e. which plugins and themes are installed and active). It won’t be possible in all situations.

Advisory timeline

  • 2016-10-07: Discovered
  • 2016-11-01: Reported
  • 2016-11-02: Vendor reported fixed
  • 2016-11-17: Requested CVE
  • 2016-11-17: Advisory published

Mitigation/further actions

Upgrade to version or later.