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CVE PROGRAM SOURCE RECORD6.5 Medium

CVE-2026-40017

An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU di

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Status
Published
Published
Updated
Assigning organization
OX

Description

An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU disproportionate to the size of the message. This is a separate issue from CVE-2026-40014 and is not addressed by that fix. Whenever a mail client issues a THREAD command on the affected mailbox, this can cause degradation or denial of service for IMAP. Monitor system for abnormal CPU usage, kill the offending process and remove the offending message from the affected mailbox. Update to non-vulnerable version. No publicly available exploits are known.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Open-Xchange GmbH OX Dovecot Pro

Default version status: unaffected

  • 2.3.0 to < 2.3.22.2affected
  • 3.0.0 to < 3.0.7affected
  • 3.1.0 to < 3.1.6affected

Open-Xchange GmbH OX Dovecot CE

Default version status: unaffected

  • 2.3.0 to < 2.4.5affected

References