Is there a patch available for CVE-2026-29136?

Yes, a patch is available for CVE-2026-29136. Update the affected software to the latest version immediately.

Seppmail CVE-2026-29136

Q: What is the CVSS score of CVE-2026-29136?

CVE-2026-29136 has a CVSS 4.0 base score of 5.3 (Medium). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/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. EPSS exploitation probability: 0.0%.

EUVD-2026-18152 MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-04-02 NCSC.ch

XSS Seppmail Secure Email Gateway

5.3

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

5.3 MEDIUM

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Scope

Lifecycle Timeline

Patch available

Apr 16, 2026 - 05:29 EUVD

15.0.3

EUVD ID Assigned

Apr 02, 2026 - 09:00 euvd

EUVD-2026-18152

Analysis Generated

Apr 02, 2026 - 09:00 vuln.today

CVE Published

Apr 02, 2026 - 08:53 nvd

MEDIUM 5.3

DescriptionCVE.org

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

AnalysisAI

SEPPmail Secure Email Gateway before version 15.0.3 allows unauthenticated attackers to inject arbitrary HTML into notification emails about new CA certificates, enabling stored cross-site scripting (XSS) attacks against email recipients. An attacker with the ability to trigger CA certificate notifications can craft malicious HTML payloads that execute when recipients view the notification email, potentially leading to credential theft, malware distribution, or further compromise of email infrastructure. No public exploit code or active exploitation has been confirmed at the time of analysis.

Technical ContextAI

The vulnerability stems from insufficient input sanitization in the CA certificate notification email generation mechanism within SEPPmail Secure Email Gateway (CWE-79: Improper Neutralization of Input During Web Page Generation). The email notification system fails to properly encode or filter HTML special characters when composing messages about new certificate authority certificate updates, allowing an attacker to inject arbitrary HTML tags and JavaScript. This is a stored XSS vulnerability because the malicious payload persists in the notification email rather than being reflected in a single request. The affected product is the complete SEPPmail Secure Email Gateway application suite running on versions prior to 15.0.3, which handles email encryption, gateway functions, and certificate management across enterprise deployments.

RemediationAI

Vendor-released patch: SEPPmail Secure Email Gateway version 15.0.3 or later. Upgrade immediately to version 15.0.3 to remediate the HTML injection vulnerability in CA certificate notification emails. The fix addresses the input sanitization deficiency in the notification email generation process. For organizations unable to upgrade immediately, review access controls to the CA certificate management functions to limit who can trigger notifications, and educate email administrators not to click suspicious links or download content from CA certificate notification emails. Detailed patch information and upgrade instructions are available in the SEPPmail release notes at https://downloads.seppmail.com/extrelnotes/150/ERN15.0.html#seppmail-vulnerability-disclosure-1503.