CVE-2026-26312 MEDIUM

CVE-2026-26312: Stalwart Mail Server has Out-of-Memory Denial of Service via Malformed Nested MIME Messages

Vendor Stalwartlabs
Product stalwart
Weakness CWE-770 · Uncontrolled resource consumption
Published February 19, 2026
Last update February 20, 2026

CVSS base score

6.5/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

Stalwart is a mail and collaboration server. A denial-of-service vulnerability exists in Stalwart Mail Server versions 0.13.0 through 0.15.4 where accessing a specially crafted email containing malformed nested `message/rfc822` MIME parts via IMAP or JMAP causes excessive CPU and memory consumption, potentially leading to an out-of-memory condition and server crash. The malformed structure causes the `mail-parser` crate to produce cyclical references in its parsed representation, which Stalwart then follows indefinitely. Version 0.15.5 contains a patch.

Key dates

02Disclosure timeline

February 19, 2026 CVE published
February 20, 2026 Record updated