CVE-2026-33209 Avo has a XSS vulnerability on `return_to` param
Attackers can inject arbitrary JavaScript via the return_to parameter in Avo admin panels, leading to script execution when users click navigation buttons.
- 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
- Available
What is CVE-2026-33209?
CVE-2026-33209 is a medium-severity cross-site scripting vulnerability in avo-hq avo, published on 20 Mar 2026. 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
Avo is a framework to create admin panels for Ruby on Rails apps. Prior to version 3.30.3, a reflected cross-site scripting (XSS) vulnerability exists in the return_to query parameter used in the avo interface. An attacker can craft a malicious URL that injects arbitrary JavaScript, which is executed when he clicks a dynamically generated navigation button. This issue has been patched in version 3.30.3.
Weakness: CWE-79
Which versions are affected by CVE-2026-33209?
2 open source packages ship an affected version, including avo. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
avo RubyGems | All versions | 3.30.3 |
avo RubyGems | All versions | 3.30.3 |
Products include Avohq Avo.
How do I fix CVE-2026-33209?
Upgrade avo to 3.30.3 or later.
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-2026-33209 being exploited?
There is no known exploitation of CVE-2026-33209 in the wild and no public exploit code.
Other vulnerabilities in avo-hq avo
- CVE-2023-34102 Possible unsafe reflection / partial denial of service in avo
- CVE-2024-22191 Stored cross-site scripting (XSS) in `key_value` field in Avo
- CVE-2023-34103 Stored XSS (Cross Site Scripting) in html content based fields of avo
- CVE-2024-22411 Cross site scripting in Action messages on Avo
Sources
Also known as GHSA-762r-27w2-q22j.