What is the CVSS score of CVE-2026-27444?

CVE-2026-27444 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-27444?

Within 24 hours: Identify all SEPPmail Secure Email Gateway deployments and their versions; notify security and email operations teams; assess current version against 15.0.1 threshold. Within 7 days: Implement compensating controls (see below); document all affected systems; establish daily monitoring for suspicious email authentication anomalies. Within 30 days: Contact SEPPmail for patch availability and deployment timeline; conduct email security architecture review; consider vendor alternative assessment if patches remain unavailable.

Seppmail CVE-2026-27444

HIGH

Interpretation Conflict (CWE-436)

2026-03-04 vulnerability@ncsc.ch

Information Disclosure Seppmail

7.5

CVSS 3.1 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Craft malicious email with spoofed headers
Exploit

SEPPmail misinterprets email address
Execution

Bypass authentication checks
Impact

Forge sender identity or decrypt message content

Vulnerability Assessment

Weakness	CWE CWE-436 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V4 - API and Web Service Interpretation consistency
Exploitation Conditions	SEPPmail Secure Email Gateway versions before 15.0.1 with default email header processing enabled. No authentication required; remote exploitation possible against any instance receiving external emails.
Impact	CVSS 7.5 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None.
Exploit ScenarioDerived	An attacker could exploit this vulnerability to fake the source of the email or decrypt it.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

SEPPmail Secure Email Gateway versions before 15.0.1 misinterpret email addresses in message headers, enabling attackers to spoof sender identities or decrypt encrypted communications due to inconsistent header parsing with standard mail infrastructure. This unauthenticated network-based vulnerability affects all default installations with no available patch, presenting significant risk to organizations relying on the gateway for email security.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 22:05 CVSS 7.5

SEPPmail Secure Email Gateway before version 15.0.1 incorrectly interprets email addresses in the email headers, causing an interpretation conflict with other mail infrastructure that allows an attacker to fake the source of the email or decrypt it. [CVSS 7.5 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Classified as CWE-436 (Interpretation Conflict). Affects Seppmail. SEPPmail Secure Email Gateway before version 15.0.1 incorrectly interprets email addresses in the email headers, causing an interpretation conflict with other mail infrastructure that allows an attacker to fake the source of the email or decrypt it.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

DescriptionCVE.org

Executive ViewAI

Why It Matters

CVE-2026-27444 affects SEPPmail Secure Email Gateway installations and allows attackers to spoof email senders or decrypt messages by exploiting email header interpretation flaws. This directly undermines email authentication controls and exposes the organization to business email compromise, data theft, and regulatory compliance violations. Immediate action is required as no vendor patch is currently available.

Business Impact: High

Compensating Controls

Enable DMARC, SPF, and DKIM enforcement with strict rejection policies on inbound mail; implement email header analysis rules to detect malformed source addresses; segment SEPPmail appliances from untrusted networks; disable encrypted message features if not operationally critical; enable comprehensive email logging and SIEM alerting for authentication failures; consider deploying secondary email gateway with independent header validation; restrict administrative access to SEPPmail configuration; establish daily email authentication audits.

Threat Intelligence Overview

EPSS Score

0.0%

Top 88% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +38

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.