Review reviewHigh

CVE-2026-35389

bulwarkmail webmail

Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server. Prior to 1.4.11, S/MIME signature verification did not validate the certificate trust chain (checkChain: false). Any email signed with a self-signed or untrusted certificate was displayed as having a valid signature. This vulnerability is fixed in 1.4.11.

CVSS
8.7
EPSS
0.18%
7.49% percentile
CISA KEV
Not listed
Published
2026.04.07
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.18%
Technical severityCVSS 8.7

Vulnerability overview

Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server. Prior to 1.4.11, S/MIME signature verification did not validate the certificate trust chain (checkChain: false). Any email signed with a self-signed or untrusted certificate was displayed as having a valid signature. This vulnerability is fixed in 1.4.11.

Affected product and versions

Product
bulwarkmail webmail
Affected versions
>= < 1.4.11, < 1.4.11
Fixed versions
1.4.11

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that bulwarkmail webmail and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE
CWE-295
CVE-2026-35389 — bulwarkmail webmail | SECUFOCUS NOW