CVE-2026-27856
HIGHDescription
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.
How to fix
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 33% of all known CVEs.
References
Related Vulnerabilities
Other CWE-287 (Improper Authentication) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-35082 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2023-35078 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2017-7921 | Critical | 9.8 | 100% | KEV | - |
| CVE-2024-7593 | Critical | 9.8 | 100% | KEV | - |
| CVE-2023-46805 | High | 8.2 | 100% | KEV + Ransom | - |
| CVE-2022-40684 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
Common questions
How do I fix CVE-2026-27856?
Published advisories record a fix for 25 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-27856 being actively exploited?
Not that we know of. CVE-2026-27856 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.39% is the estimated probability that it will be exploited in the next 30 days. That is higher than 33% of all scored CVEs.
How severe is CVE-2026-27856?
CVE-2026-27856 has a CVSS v3 base score of 7.4, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-27856 affect?
Published advisories record a fix for dovecot (Amazon), dovecot-debuginfo (Amazon), dovecot-debugsource (Amazon), dovecot-devel (Amazon), and 21 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.