SRC-2018-0032 : Vanilla Forums Gdn_Format unserialize Unserialize Remote Code Execution Vulnerability

CVE ID:

CVE-2018-19499

CVSS Score:

6.6, (AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H)

Affected Vendors:

Vanilla

Affected Products:

Vanilla Forums

Vulnerability Details:

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Vanilla Forums. Authentication is required to exploit this vulnerability, however the authentication can be bypassed.

The specific flaw exists within the unserialize function of the Gdn_Format class. The issue results in an unserialize via a crafted phar archive. An attacker can leverage this vulnerability to execute code under the context of the web server.

Vendor Response:

Vanilla has issued an update to correct these vulnerabilities. More details can be found at:
https://github.com/vanilla/vanilla/commit/e8b4c23d9b68c8cc904e76d9e012538e426e8303

Disclosure Timeline:

• 2018-08-08 - Vulnerability reported to Vanilla
• 2018-08-17 - Vulnerability patched
• 2018-11-23 - Coordinated public release of advisory

Proof of Concept:

https://hackerone.com/reports/407552

Credit:

This vulnerability was discovered by Steven Seeley (mr_me) of Source Incite