CVE-2026-29137 Long Subject Untagging

Medium 5.3 Published 2 Apr 2026 Updated 2 Apr 2026

Attackers can hide security tags from users by crafting long email subjects, bypassing security warnings 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-2026-29137?

CVE-2026-29137 is a medium-severity 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 hide security tags from users by crafting a long subject.

Weakness: CWE-20

Which versions are affected by CVE-2026-29137?

It affects 1 product.

Products include Seppmail Secure Email Gateway.

How do I fix CVE-2026-29137?

No fix has been published for CVE-2026-29137 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-29137 being exploited?

There is no known exploitation of CVE-2026-29137 in the wild and no public exploit code.

Sources

Also known as GHSA-j47q-h9j2-79x8.