Is CVE-2026-35389 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-35389 being exploited in the wild.

How severe is CVE-2026-35389?

High severity, with a CVSS score of 7.5, published 6 April 2026.

Is there a fix for CVE-2026-35389?

A patch was published on 2026-04-06: Fix released in version 1.4.11 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-35389 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-35389?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-35389: Bulwark Webmail improper certificate validation in S/MIME verification

CVE-2026-35389 · Severity: high · CVSS 7.5 · Published 2026-04-06

Bulwark Webmail, a self-hosted email client, failed to properly verify the authenticity of digitally signed emails. This allowed attackers to send fraudulent emails using untrusted or self-signed certificates that would appear to the recipient as having a valid, trusted signature. This could be used to conduct highly convincing phishing or impersonation attacks against users of the mail system.

Quick answers

Is CVE-2026-35389 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-35389 being exploited in the wild.
How severe is CVE-2026-35389?: High severity, with a CVSS score of 7.5, published 6 April 2026.
Which products and versions are affected?: Bulwark Webmail < 1.4.11.
Is there a fix for CVE-2026-35389?: A patch was published on 2026-04-06: Fix released in version 1.4.11 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-35389 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-35389?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability in Bulwark Webmail prior to version 1.4.11 was caused by improper certificate validation (CWE-295) in the S/MIME signature verification component. Specifically, the 'checkChain' parameter in 'lib/smime/smime-verify.ts' was set to false, bypassing the validation of the certificate trust chain. A remote attacker could send an email signed with a self-signed or otherwise untrusted certificate, and the webmail interface would incorrectly display it as having a valid signature. This allows for the spoofing of signed communications. The issue is resolved in version 1.4.11 by setting 'checkChain' to true.

Affected products

Bulwark Webmail < 1.4.11

Timeline

2026-04-02: advisory: GitHub Security Advisory published
2026-04-06: disclosed: NVD publication date
2026-04-06: patched: Fix released in version 1.4.11

References

https://github.com/bulwarkmail/webmail/security/advisories/GHSA-v6w6-338p-p256

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