CVE-2026-27856

EUVD-2026-16565
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.4 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 31.93%
Affected Products (NVD)
VendorProductVersion
dovecotdovecot
𝑥
< 2.4.3
open-xchangedovecot
𝑥
< 2.3.22.1
open-xchangedovecot
3.0.0 ≤
𝑥
< 3.0.5
open-xchangedovecot
3.1.0 ≤
𝑥
< 3.1.4
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle Support
1:2.2.36-8.el7_9.1 ≤
𝑥
< *
ADP
Debian logo
Debian Releases
Debian Product
Codename
dovecot
bookworm
1:2.3.19.1+dfsg1-2.1+deb12u6
fixed
bookworm (security)
1:2.3.19.1+dfsg1-2.1+deb12u6
fixed
bullseye
vulnerable
bullseye (security)
1:2.3.13+dfsg1-2+deb11u4
fixed
forky
1:2.4.4+dfsg1-2
fixed
sid
1:2.4.4+dfsg1-2
fixed
trixie
1:2.4.1+dfsg1-6+deb13u6
fixed
trixie (security)
1:2.4.1+dfsg1-6+deb13u6
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
dovecot
bionic
not-affected
focal
needed
jammy
Fixed 1:2.3.16+dfsg1-3ubuntu2.7
released
noble
Fixed 1:2.3.21+dfsg1-2ubuntu6.3
released
questing
Fixed 1:2.4.1+dfsg1-5ubuntu4.1
released
resolute
not-affected
trusty
not-affected
xenial
not-affected
openSUSE logo
openSUSE / SLES Releases
openSUSE Product
Release
dovecot22
suse enterprise server 12 SP3
2.2.31-19.32.1
fixed
suse enterprise server 12 SP5
2.2.31-19.32.1
fixed
dovecot22-backend-mysql
suse enterprise server 12 SP3
2.2.31-19.32.1
fixed
suse enterprise server 12 SP5
2.2.31-19.32.1
fixed
dovecot22-backend-pgsql
suse enterprise server 12 SP3
2.2.31-19.32.1
fixed
suse enterprise server 12 SP5
2.2.31-19.32.1
fixed
dovecot22-backend-sqlite
suse enterprise server 12 SP3
2.2.31-19.32.1
fixed
suse enterprise server 12 SP5
2.2.31-19.32.1
fixed
dovecot22-devel
suse enterprise server 12 SP5
2.2.31-19.32.1
fixed
Amazon Linux logo
Amazon Linux Releases
Amazon Package
Release
dovecot
Amazon Linux 2
1:2.2.36-6.amzn2.1.3
fixed
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-debuginfo
Amazon Linux 2
1:2.2.36-6.amzn2.1.3
fixed
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-debugsource
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-devel
Amazon Linux 2
1:2.2.36-6.amzn2.1.3
fixed
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-mysql
Amazon Linux 2
1:2.2.36-6.amzn2.1.3
fixed
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-mysql-debuginfo
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-pgsql
Amazon Linux 2
1:2.2.36-6.amzn2.1.3
fixed
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-pgsql-debuginfo
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-pigeonhole
Amazon Linux 2
1:2.2.36-6.amzn2.1.3
fixed
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
dovecot-pigeonhole-debuginfo
Amazon Linux 2023
1:2.3.20-1.amzn2023.0.3
fixed
Common Weakness Enumeration
References
https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
https://access.redhat.com/errata/RHSA-2026:26564
https://access.redhat.com/security/cve/CVE-2026-27856
https://bugzilla.redhat.com/show_bug.cgi?id=2452171
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27856.json