# CVE-2026-125393: MailEnable Enterprise Premium heap overflow in IMAP X-FB-FETCH

Source: https://junglewise.ai/threats/cve-2026-125393-mailenable-enterprise-premium-before-10-62-contains-a-heap  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-125393 · Severity: medium · CVSS 6.5 · Published 2026-11-10

MailEnable Enterprise Premium is a mail server that provides IMAP email access to corporate users. An authenticated attacker can crash the IMAP service by sending a specially crafted command with an excessively long user address, causing email service disruption and denial of service.

Vendors: [MailEnable](https://junglewise.ai/threats/vendors/mailenable).

## Quick answers

**Is CVE-2026-125393 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-125393 being exploited in the wild.

**How severe is CVE-2026-125393?** Medium severity, with a CVSS score of 6.5, published 10 November 2026.

**Which products and versions are affected?** MailEnable Enterprise Premium before 10.62.

**Is there a fix for CVE-2026-125393?** Yes: fixed in 10.62. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-125393 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-125393?** Check whether you run MailEnable Enterprise Premium at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 10.62

## Technical details

A heap-based buffer overflow exists in the IMAP X-FB-FETCH command handler when processing the X-FB-USER parameter without length validation. An authenticated attacker can supply an X-FB-USER address longer than approximately 1016 bytes to overflow a fixed 0x400-byte heap buffer, crashing the IMAP service. The vulnerability requires valid user credentials to exploit.

## Affected products

- MailEnable Enterprise Premium before 10.62

## Timeline

- 2026-11-10: disclosed
- 2026-11-03: patched

## References

- [https://www.mailenable.com/Premium-ReleaseNotes.txt](https://www.mailenable.com/Premium-ReleaseNotes.txt)
- [https://www.vulncheck.com/advisories/mailenable-enterprise-premium-before-10.62-heap-overflow-via-imap-x-fb-fetch](https://www.vulncheck.com/advisories/mailenable-enterprise-premium-before-10.62-heap-overflow-via-imap-x-fb-fetch)

## Related threats

- [MailEnable Enterprise Premium auth bypass in WebAdmin mobile portal](https://junglewise.ai/threats/cve-2026-44400-mailenable-enterprise-premium-auth-bypass-in-webadmin-mobile)