Vulnerability found:
12 November 2007

Vendor informed:
19 November 2007

Severity level:

Jan Fry of ProCheckUp Ltd (

Sites using sIFR to render fonts/text are vulnerable to a vanilla XSS within the "txt" parameter processed by the actionscript in the '<fontname>.swf' flash file.


An attacker may be able to cause execution of malicious scripting code in the browser of a user who clicks on a link to the target website, or visits a malicious website that requests such link.

This type of attack can result in non-persistent defacement of the target site, or the redirection of confidential information (i.e.: session IDs) to unauthorised third parties.




the victim user does NOT need to be authenticated for this vulnerability to be exploitable.

CVE reference


Successfully tested on

sIFR 2.0.2

Proof of concept:
{att:bold}- HTML injection PoC {att:/bold}

Provided the victim is tricked to load the following URL, he/she would be redirected to a third-party site.

https://target.tld/<fontname>.swf?txt=<a href="">click me!</a>

{att:bold}- XXS PoC {att:/bold}


How to fix:
This vulnerability has been fixed on Novemberborn sIFR 2.0.3 and Novemberborn sIFR 3r278.


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