CVE-2020-15139 XSS in MyBB
Attackers can execute arbitrary scripts in victims' browsers via malicious MyCode in MyBB forums, potentially leading to session hijacking or data theft.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2020-15139?
CVE-2020-15139 is a high-severity cross-site scripting vulnerability in Mybb Mybb, published on 10 Aug 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
In MyBB before version 1.8.24, the custom MyCode (BBCode) for the visual editor doesn't escape input properly when rendering HTML, resulting in a DOM-based XSS vulnerability. The weakness can be exploited by pointing a victim to a page where the visual editor is active (e.g. as a post or Private Message) and operates on a maliciously crafted MyCode message. This may occur on pages where message content is pre-filled using a GET/POST parameter, or on reply pages where a previously saved malicious message is quoted. After upgrading MyBB to 1.8.24, make sure to update the version attribute in the `codebuttons` template for non-default themes to serve the latest version of the patched `jscripts/bbcodes_sceditor.js` file.
Weakness: CWE-79
Which versions are affected by CVE-2020-15139?
It affects 1 product.
Products include Mybb Mybb.
How do I fix CVE-2020-15139?
No fix has been published for CVE-2020-15139 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2020-15139 being exploited?
There is no known exploitation of CVE-2020-15139 in the wild and no public exploit code.
Other vulnerabilities in Mybb Mybb
Sources
Also known as CVE-2020-17447, GHSA-37h7-vfv6-f8rj.