Bug 2452175 (CVE-2026-27858)

Summary: CVE-2026-27858 dovecot: denial of service via crafted message before authentication
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in dovecot. An unauthenticated and remote attacker can send a crafted message that causes managesieve to allocate an excessive amount of memory, forcing managesieve-login to be unavailable by repeatedly crashing the process, resulting in a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2452240, 2452241, 2452242    
Bug Blocks:    

Description OSIDB Bzimport 2026-03-27 09:02:09 UTC
Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.
 Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.