Medium severity · published Mar 27, 2026
CVE-2026-27856
Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack
5.9
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 34% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OD
OX Dovecot Pro · Open-Xchange GmbH
through 2.3.0 · source: vendor
DO
Dovecot · Dovecot
before 2.4.3 · source: NVD
RH
Red Hat Enterprise Linux 6 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 7 Extended Lifecycle Support · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27856
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27856
Vendor Advisory
https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:26564
access.redhat.com
https://access.redhat.com/security/cve/CVE-2026-27856
bugzilla.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2452171
security.access.redhat.com
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27856.json
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