Bug 2525579 (CVE-2026-52687)

Summary: CVE-2026-52687 dovecot: dovecot: Denial of Service via IMAP compression memory exhaustion
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
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in dovecot. A remote attacker with valid credentials can exploit this vulnerability by selecting a compression algorithm for the IMAP connection that requires a large amount of memory for decompression. By opening several such connections, the attacker can exhaust the process's memory limit, leading to the termination of the process and all its connections. This can cause degradation or a complete denial of service for IMAP.
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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: 2526689    
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Description OSIDB Bzimport 2026-08-28 11:23:52 UTC 
An attacker that has valid credentials can select a compression algorithm for the IMAP connection whose decompression state requires a large amount of memory, and open several such connections. The memory limit of the process is reached with only a few connections, terminating the process and all connections it handles, which can cause degradation or denial of service for IMAP. Disable IMAP compression. Alternatively limit the number of connections handled by a single imap-login process, though this has a performance impact. Update to non-vulnerable version. No publicly available exploits are known.