Bug 2525543 (CVE-2026-40014)

Summary: CVE-2026-40014 dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Dovecot. A remote attacker, by sending a specially crafted email message header to a user, can cause the Internet Message Access Protocol (IMAP) THREAD command to consume excessive CPU resources. When a mail client processes this message, it can lead to degradation or a denial of service for the IMAP server.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2526673    
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Description OSIDB Bzimport 2026-08-28 11:21:58 UTC 
An attacker that can send mail to a user can craft a message header that makes the IMAP THREAD command consume CPU disproportionate to the size of the message. When 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.