CVE-2026-27856: High severity Dovecot doveadm vulnerability
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Limit network access to the doveadm HTTP service port to reduce exposure to timing oracle credential disclosure.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-27856?
CVE-2026-27856 is classified as a high-severity vulnerability due to its potential to allow unauthorized access to sensitive credentials.
How do I fix CVE-2026-27856?
To mitigate CVE-2026-27856, limit access to the doveadm HTTP service port and consider implementing additional authentication methods.
What systems are affected by CVE-2026-27856?
CVE-2026-27856 affects the Dovecot doveadm service, particularly versions that utilize direct comparison for credential verification.
What type of attack does CVE-2026-27856 enable?
CVE-2026-27856 allows attackers to potentially exploit a timing oracle attack to infer valid credentials.
What are the potential impacts of CVE-2026-27856?
Successful exploitation of CVE-2026-27856 can lead to full access to the affected Dovecot components and sensitive user data.