S/MIME Verification Flaw in Bulwark Webmail by Stalwart Mail Server
CVE-2026-35389

8.7HIGH

Key Information:

Vendor

Bulwarkmail

Status
Webmail
Vendor
CVE Published:
6 April 2026

What is CVE-2026-35389?

Bulwark Webmail, a webmail client for Stalwart Mail Server, had a vulnerability that allowed S/MIME signatures from self-signed or untrusted certificates to be incorrectly validated. This flaw, present in versions prior to 1.4.11, failed to verify the certificate trust chain, potentially misleading users into believing that untrusted emails were secure. The issue was resolved in version 1.4.11, and users are encouraged to update to the latest version to ensure proper security.

Affected Version(s)

webmail < 1.4.11

References

https://github.com/bulwarkmail/webmail/security/advisorie...
x_refsource_CONFIRM

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.