CVE-2026-33607
Received Received - Intake

IMAP CPU Exhaustion via LIST Command in Open-Xchange

Publication date: 2026-08-28

Last updated on: 2026-08-28

Assigner: Open-Xchange

Description
An attacker that has valid credentials can use IMAP LIST command to consume CPU. This can cause degradation or denial of service for IMAP. Monitor system for abnormal CPU usage and kill the offending process and lock account. Alternatively install fixed version. No publicly available exploits are known.

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Meta Information

Published
2026-08-28
Last Modified
2026-08-28
Generated
2026-08-28
AI Q&A
2026-08-28
EPSS Evaluated
N/A
NVD
CVE-2026-33607
EUVD
EUVD-2026-67662

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.

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Executive Summary

This vulnerability allows an attacker with valid credentials to exploit the IMAP LIST command, causing high CPU consumption. This can degrade system performance or lead to a denial of service for IMAP services.

Detection Guidance

Monitor system CPU usage for abnormal spikes. Use commands like 'top', 'htop', or 'ps aux' to identify processes consuming excessive CPU. Check IMAP service logs for repeated LIST command usage.

Impact Analysis

It can cause system slowdowns or crashes due to excessive CPU usage. Users may experience degraded IMAP service performance or complete unavailability. Affected accounts should be locked and processes terminated.

Mitigation Strategies

Kill the offending process consuming high CPU and lock the associated user account. Install the fixed version of the IMAP service to prevent recurrence.

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