Denial-of-Service Vulnerability in Stalwart Mail Server by Stalwart Labs
CVE-2026-26312

6.5MEDIUM

Key Information:

Vendor

Stalwartlabs

Status
Stalwart
Vendor
CVE Published:
19 February 2026

What is CVE-2026-26312?

A denial-of-service vulnerability exists in Stalwart Mail Server versions 0.13.0 through 0.15.4. This flaw can be exploited when a specially crafted email containing malformed nested 'message/rfc822' MIME parts is accessed via IMAP or JMAP. The malformed structure leads to excessive CPU and memory consumption due to cyclical references generated by the 'mail-parser' crate, which Stalwart Mail Server follows indefinitely, potentially resulting in an out-of-memory condition and server crash. Users are advised to upgrade to version 0.15.5 or higher, which includes a patch for this vulnerability.

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Affected Version(s)

stalwart >= 0.13.0, < 0.15.5

References

https://github.com/stalwartlabs/stalwart/security/advisor...
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CVSS V3.1

Score:
6.5
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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