CVE-2026-29136 CA Notification HTML Injection

Medium 5.3 Published 2 Apr 2026 Updated 2 Apr 2026

Attackers can inject HTML into CA certificate notification emails, potentially executing scripts or bypassing security controls in SEPPmail Secure Email Gateway.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2026-29136?

CVE-2026-29136 is a medium-severity cross-site scripting vulnerability in SEPPmail Secure Email Gateway, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

SEPPmail Secure Email Gateway before version 15.0.3 allows an attacker to inject HTML into notification emails about new CA certificates.

Weakness: CWE-79

Which versions are affected by CVE-2026-29136?

It affects 1 product.

Products include Seppmail Secure Email Gateway.

How do I fix CVE-2026-29136?

No fix has been published for CVE-2026-29136 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-29136 being exploited?

There is no known exploitation of CVE-2026-29136 in the wild and no public exploit code.

Sources

Also known as GHSA-9cfw-4wfr-8gwf.