Headline
CVE-2023-34461: XSS Availability in Post Creation and Viewing.
PyBB is an open source bulletin board. A manual code review of the PyBB bulletin board server has revealed that a vulnerability could have been exploited in which users could submit any type of HTML tag, and have said tag run. For example, a malicious <a> that looks like <a href=javascript:alert (1)>xss</a> could have been used to run code through JavaScript on the client side. The problem has been patched as of commit 5defd92, and users are advised to upgrade. Attackers do need posting privilege in order to exploit this vulnerability. This vulnerability is present within the 0.1.0 release, and users are advised to upgrade to 0.1.1. Users unable to upgrade may be able to work around the attack by either; Removing the ability to create posts, removing the |safe tag from the Jinja2 template titled “post.html” in templates or by adding manual validation of links in the post creation section.
Impact
Manual code review of the PyBB bulletin board server has revealed that a vulnerability could have been exploited in which users could submit any type of HTML tag, and have said tag run. For example, a malicious <a> that looks like <a href=javascript:alert (1)>xss</a> could have been used to run code through JavaScript on the client side.
Patches
The problem has now been patched as of commit 5defd92, and users are advised to upgrade to said version. This vulnerability IS found within the 0.1.0 release, and users are advised to update to 0.1.1.
Workarounds
Users are able to work around the attack by either;
- Removing the ability to create posts.
- Removing the |safe tag from the Jinja2 template titled “post.html” in templates.
- Adding manual validation of links in the post creation section.
References
OWASP XSS Article https://owasp.org/
Wikipedia XSS https://en.wikipedia.org/