CyberSecBulletin
CVE-2026-44129NVD status: Deferred

Secure Email Gateway: Improper Neutralization of Special Elements Used in a Template Engine

Published Updated By the CyberSecBulletin desk

CVE-2026-44129 is a high-severity improper neutralization of special elements used in a template engine vulnerability in Secure Email Gateway from SeppMail, with a CVSS 4.0 base score of 8.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 15.0.4 as the first without the flaw, so updating Secure Email Gateway to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.53% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Secure Email Gateway to 15.0.4 or a later version.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
SEPPmailSecure Email Gatewaybefore 15.0.415.0.4

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Attack requirements
PresentThe target must be in a specific state or configuration for the attack to work.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Confidentiality (vulnerable system)
HighSerious loss of confidentiality on the vulnerable system.
Integrity (vulnerable system)
LowLimited loss of integrity on the vulnerable system.
Availability (vulnerable system)
LowLimited loss of availability on the vulnerable system.
Confidentiality (other systems)
NoneNo loss of confidentiality on systems beyond the vulnerable one.
Integrity (other systems)
NoneNo loss of integrity on systems beyond the vulnerable one.
Availability (other systems)
NoneNo loss of availability on systems beyond the vulnerable one.

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:L/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. Scored by CNA (ncsc.ch).

Official description

SEPPmail Secure Email Gateway before version 15.0.4 contains a server-side template injection vulnerability in the new GINA UI because an endpoint accepts attacker-controlled template, allowing remote attackers to execute arbitrary template expressions and potentially achieve remote code execution depending on the enabled template plugins.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Special Elements Used in a Template Engine

The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.

How developers prevent this class of flaw

  • Choose a template engine that offers a sandbox or restricted mode, or at least limits the power of any available expressions, function calls, or commands.
  • Use the template engine's sandbox or restricted mode, if available.

More Improper Neutralization of Special Elements Used in a Template Engine vulnerabilities (CWE-1336)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Secure Email Gateway

All Secure Email Gateway vulnerabilities

Recent Improper Neutralization of Special Elements Used in a Template Engine vulnerabilities

Spotted an error? Tell us.