Medium [CVE-2026-33607] Denial of Service via IMAP LIST command
This medium-severity Red Hat Linux advisory covers CVE-2026-33607 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
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. A flaw was found in Dovecot.
Red Hat severity: Moderate — CVSS 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L). Weakness: CWE-606.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9. Will not fix / out of support: Red Hat Enterprise Linux 6.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: dovecot.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 44 minutes ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 44 minutes ago·verify at source
Mitigation checklist
- To mitigate this issue, restrict access to the Dovecot IMAP service to trusted networks or localhost using firewall rules or Dovecot's configuration. Additionally, implement system monitoring for abnormal CPU utilization by Dovecot processes to detect and respond to potential exploitation attempts. If network configuration changes are applied, a restart of the Dovecot service may be required.
Official advisory · high-confidence parse· fetched 44 minutes ago·verify at source
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