CVE-2021-47784 Cyberfox Web Browser 52.9.1 - Denial of Service (PoC)
Attackers can crash the Cyberfox Web Browser by pasting a large payload into the search bar, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2021-47784?
CVE-2021-47784 is a medium-severity denial of service vulnerability in Cyberfox Web Browser, published on 15 Jan 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Cyberfox Web Browser 52.9.1 contains a denial of service vulnerability that allows attackers to crash the application by overflowing the search bar with excessive data. Attackers can generate a 9,000,000 byte payload and paste it into the search bar to trigger an application crash.
Weakness: CWE-770
Which versions are affected by CVE-2021-47784?
How do I fix CVE-2021-47784?
No fix has been published for CVE-2021-47784 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-47784 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47784 exists.
Sources
Also known as GHSA-2mg9-fchf-m4w9.