What is CVE-2026-27857?

CVE-2026-27857 is a medium-severity vulnerability in Dovecot, classified under Uncontrolled Resource Consumption. CVSS score: 4.3/10. Published 2026-03-27.

How severe is CVE-2026-27857?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Resource exhaustion in Dovecot

CVE-2026-27857

Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command e…

Vulnerability class: DoS (Denial of Service)

EPSS: 0.000 (10.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.

Affected products

Dovecot
Open-xchange Dovecot
Open-xchange Gmbh Ox Dovecot Pro — versions 0

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

References

security@open-xchange.com (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-27857?: CVE-2026-27857 is a medium-severity vulnerability in Dovecot, classified under Uncontrolled Resource Consumption. CVSS score: 4.3/10. Published 2026-03-27.
How severe is CVE-2026-27857?: Medium severity. CVSS v3 base score is 4.3 out of 10.