CVE-2026-35389 Bulwark Webmail S/MIME signature verification accepted self-signed certificates
Attackers can spoof signed emails by using self-signed certificates, bypassing S/MIME signature verification in Bulwark Webmail.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-35389?
CVE-2026-35389 is a high-severity vulnerability in bulwarkmail webmail, published on 6 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-295
Which versions are affected by CVE-2026-35389?
It affects 1 product.
Products include Bulwarkmail Webmail.
How do I fix CVE-2026-35389?
No fix has been published for CVE-2026-35389 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-35389 being exploited?
There is no known exploitation of CVE-2026-35389 in the wild and no public exploit code.
Other vulnerabilities in bulwarkmail webmail
- CVE-2026-35391 Security feature bypass in webmail
- CVE-2026-34833 Bulwark Webmail: Information Exposure: password returned in /api/auth/session
- CVE-2026-34834 Bulwark Webmail: Authentication Bypass in verifyIdentity() due to missing cookie validation
- CVE-2026-35390 Content-Security-Policy was set to Report-Only mode, failing to block XSS attacks
Sources
Also known as GHSA-v6w6-338p-p256.