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Secure Email Gateway EUVDEUVD-2026-18148

| CVE-2026-29134 MEDIUM
Reliance on Untrusted Inputs in a Security Decision (CWE-807)
2026-04-02 NCSC.ch GHSA-v5jf-vjfx-frfr
Authentication Bypass Secure Email Gateway
5.3
CVSS 4.0 · NVD
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Severity by source

NVD PRIMARY
5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/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

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/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
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

4
Patch available
Apr 16, 2026 - 05:29 EUVD
15.0.3
EUVD ID Assigned
Apr 02, 2026 - 08:45 euvd
EUVD-2026-18148
Analysis Generated
Apr 02, 2026 - 08:45 vuln.today
CVE Published
Apr 02, 2026 - 08:29 nvd
MEDIUM 5.3

DescriptionCVE.org

SEPPmail Secure Email Gateway before version 15.0.3 allows an external user to modify GINA webdomain metadata and bypass per-domain restrictions.

AnalysisAI

SEPPmail Secure Email Gateway before version 15.0.3 allows unauthenticated external users to modify GINA webdomain metadata and bypass per-domain restrictions, enabling attackers to circumvent email security controls across isolated security domains. NCSC.ch reported this authentication bypass vulnerability affecting all versions prior to 15.0.3. The ability to modify domain-level metadata across organizational security boundaries represents a direct compromise of the gateway's core function to enforce per-domain policies.

Technical ContextAI

GINA (likely referring to the gateway's identity and access control layer for webdomain management) implements per-domain metadata restrictions intended to isolate email security policies across different organizational domains. The vulnerability stems from improper authorization validation (CWE-807: Reliance on Untrusted Inputs in a Security Decision) in the webdomain metadata modification functionality. This allows external users to interact with administrative metadata endpoints without proper authentication or authorization checks, bypassing the domain isolation mechanism that should enforce distinct security policies per domain. SEPPmail Secure Email Gateway is a centralized email security appliance responsible for threat detection, encryption, and policy enforcement across multiple organizational domains.

RemediationAI

Upgrade SEPPmail Secure Email Gateway to version 15.0.3 or later immediately. The vendor-released patch version 15.0.3 addresses the GINA webdomain metadata authorization flaw. No interim workarounds are documented; the core vulnerability exists in the metadata modification endpoints and requires the patched version to remediate. Organizations should consult the vendor's release notes at https://downloads.seppmail.com/extrelnotes/150/ERN15.0.html#seppmail-vulnerability-disclosure-1503 for detailed upgrade procedures and any prerequisite compatibility checks.

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EUVD-2026-18148 vulnerability details – vuln.today
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