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XSS in PDF Viewer

Low
N
Nextcloud
Submitted None
Reported by skewbed

Vulnerability Details

Technical details and impact analysis

Cross-site Scripting (XSS) - Generic
An outdated version of PDF.js in use allows for the CVE-2018-5158 vulnerability. When the payload PDF is shown in the supplied PDF viewer, it can execute arbitrary JavaScript. I have tested the payload PDF, and it is working in the Safari 13.0.5 (the latest version) and Firefox 74.0 (the latest version). Although, it does not work in the latest version of Chrome. I could not find a way to test it on the desktop client. I assume that it would use the system PDF viewer. Modifying the payload to fetch other code was luckily blocked because of a CORS policy. The payload is from [https://bugzilla.mozilla.org/show_bug.cgi?id=1452075](https://bugzilla.mozilla.org/show_bug.cgi?id=1452075). I have also included the PDF in the attachments. The payload can be seen in action by checking the JavaScript console. It says "Hello, this is code running in" followed by the path to file where the vulnerability is. ## Impact An attacker could execute arbitrary JavaScript code on a web browser when a PDF containing an exploit is opened.

Related CVEs

Associated Common Vulnerabilities and Exposures

The PDF viewer does not sufficiently sanitize PostScript calculator functions, allowing malicious JavaScript to be injected through a crafted PDF file. This JavaScript can then be run with the permissions of the PDF viewer by its worker. This vulnerability affects Firefox ESR < 52.8 and Firefox < 60.

Report Details

Additional information and metadata

State

Closed

Substate

Resolved

Bounty

$100.00

Submitted

Weakness

Cross-site Scripting (XSS) - Generic