CVE-2026-27856

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.

Published: 2026-03-27 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-27856 is rated Low Risk (37.2/100): CVSS High severity, with low exploitation likelihood (EPSS 0.29%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-27856

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.03% 0.29% +0.26%
2 2026-03-27 — 0.03% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-27856

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 5.2 [email protected]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]

Weakness enumeration for CVE-2026-27856

OS Trackers for CVE-2026-27856

vendor priority summary link
alpine — CVE-2026-27856: 1 source package rows (dovecot); 2 state rows across 2 repos (3.23-main, edge-main); fixed 2, open 0. https://security.alpinelinux.org/vuln/CVE-2026-27856
debian not yet assigned CVE-2026-27856 not yet assigned priority: Debian including 1 source packages (dovecot), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-27856
redhat high — https://access.redhat.com/security/cve/CVE-2026-27856
suse high CVE-2026-27856 severity important: SUSE including 8 source package names (dovecot24-2.4.3-1.1, dovecot24-backend-mysql-2.4.3-1.1, …), 8 product×package rows across 1 product lines (openSUSE Tumbleweed): Fixed 8. https://www.suse.com/security/cve/CVE-2026-27856/
ubuntu medium CVE-2026-27856 medium priority: Ubuntu including 1 source packages (dovecot), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): released 4, not-affected 3, needed 1. https://ubuntu.com/security/CVE-2026-27856

Affected software / configurations for CVE-2026-27856

Vendor Product Version Raw CPE
dovecot dovecot < 2.4.3 cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*
open-xchange dovecot < 2.3.22.1 cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*
open-xchange dovecot >= 3.0.0, < 3.0.5 cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*
open-xchange dovecot >= 3.1.0, < 3.1.4 cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*

References for CVE-2026-27856

cvelogic Threat Intelligence