CVE-2026-27859

A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. A suitably formatted mail message causes mail delivery process to consume large amounts of CPU time. Use MTA capabilities to limit RFC 2231 MIME parameters in mail messages, or upgrade to fixed version where the processing is limited. No publicly available exploits are known.

Published: 2026-03-27 Last update: 2026-04-30 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-27859 is rated Low Risk (22.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.02%). 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-2026-27859

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 2026-04-30 0.05% 0.02% -0.03%
2 2026-04-02 0.04% 0.05% +0.01%
3 2026-03-27 — 0.04% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-27859

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L 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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2026-27859

OS Trackers for CVE-2026-27859

vendor priority summary link
alpine — CVE-2026-27859: 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-2026-27859
debian not yet assigned CVE-2026-27859 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-2026-27859
redhat medium — https://access.redhat.com/security/cve/CVE-2026-27859
suse medium CVE-2026-27859 severity moderate: SUSE including 9 source package names (dovecot, dovecot24-2.4.3-1.1, …), 29 product×package rows across 22 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS, … (22 product lines)): Known Not Affected 21, Fixed 8. https://www.suse.com/security/cve/CVE-2026-27859/
ubuntu medium CVE-2026-27859 medium priority: Ubuntu including 1 source packages (dovecot), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): needed 4, released 4. https://ubuntu.com/security/CVE-2026-27859

Affected software / configurations for CVE-2026-27859

Vendor Product Version Raw CPE
dovecot dovecot < 2.4.3 cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*
open-xchange dovecot < 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-2026-27859

cvelogic Threat Intelligence