SeppmailApplication

CVE-2026-2743

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-05
Fix available
A fix is available. Upgrade to after 15.0.2.1 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Arbitrary File Write via Path Traversal upload to Remote Code Execution in SeppMail User Web Interface. The affected feature is the large file transfer (LFT). This issue affects SeppMail: 15.0.2.1 and before

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A path traversal vulnerability in the Large File Transfer (LFT) feature of SeppMail User Web Interface allows authenticated attackers to write arbitrary files to arbitrary locations on the filesystem, which can be leveraged to achieve remote code execution.

MitigationApply vendor-supplied patch for version 15.0.2.1 or later; if unavailable, restrict network access to the User Web Interface and implement WAF rules to block path traversal patterns in upload requests.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SeppmailApplication
Affected:<= 15.0.2.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Seppmail User Web Interface installation
    Locate the Seppmail software on the system and confirm the User Web Interface component is present
    Affected if Seppmail User Web Interface is installed on the system
  2. Check installed version
    Use the product's version checking mechanism or examine version metadata files to determine the exact version number
    Affected if The installed version is 15.0.2.1 or any earlier version
  3. Verify Large File Transfer feature status
    Access the User Web Interface administrative console and inspect whether the LFT module or feature is enabled
    Affected if The LFT feature is enabled and accessible to users
  4. Assess network accessibility of User Web Interface
    Determine if the User Web Interface is exposed to the network or internal users can reach the upload endpoints
    Affected if The User Web Interface is network-accessible without proper access restrictions
  5. Inspect for unauthorized file creation
    Review filesystem locations outside the intended upload directory for recently created files, especially in web root or system directories
    Affected if Unexpected files exist in directories not designated for user uploads

The environment is affected if Seppmail User Web Interface version 15.0.2.1 or earlier is installed with the Large File Transfer feature enabled and accessible to authenticated users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to a release after 15.0.2.1
Interim mitigation

Apply vendor-supplied patch for version 15.0.2.1 or later; if unavailable, restrict network access to the User Web Interface and implement WAF rules to block path traversal patterns in upload requests.

Fix this in Seppmail Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-2743 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-2743 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data