From: research <>

PR10-04 Directory traversal limited to file validation within Viva
thumbs WordPress add-on

Advisory publicly released: Tuesday, 21 December 2010
Vulnerability found: Thursday, 4 February 2010
Vendor informed: Monday, 8 February 2010
Severity level: Low/Medium
Richard Brain of ProCheckUp Ltd (
Viva Thumbs resizes and display images, as part of a popular WordPress
plugin.ProCheckUp has discovered that Viva Thumbs is vulnerable to a
directory traversal attack within the image display functionality, the
directory traversal attack is limited to file existence validation.

Note: tested on Viva Thumbs running on the Linux operating system.
Proof of concept
The following demonstrate the traversal flaw:

1) Vulnerable to directory traversal

The existance of files can be validated on the system, outside the
WordPress webroot.
How to fix
None available

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