Bug 2452171 (CVE-2026-27856)

Summary: CVE-2026-27856 dovecot: Doveadm: Full access via timing oracle attack in credential verification
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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A flaw was found in Doveadm, a component of Dovecot. An attacker can exploit a timing oracle vulnerability during the direct comparison of credentials. This allows the attacker to determine the configured credentials, potentially leading to full unauthorized access to the affected component.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-03-27 09:01:52 UTC 
Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can use this to determine the configured credentials. Figuring out the credential will lead into full access to the affected component. Limit access to the doveadm http service port, install fixed version. No publicly available exploits are known.