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TI-2026-28302 Aliases CVE-2026-39312

Pre-Auth EAP-TLS DoS on SoftEther VPN Developer Edition

Priority HIGH 72CWE-789Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-789.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00468 40th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
SoftEtherVPNSoftEtherVPNup to 5.2.5188—No fix listedCNA
  • SoftEtherVPN VendorSoftEtherVPN Affected up to 5.2.5188 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:softether:softethervpn:*:*:*:*:developer:*:*:*up to 5.2.5188VulnerableSoftEther VPN
  • cpe:2.3:a:softether:softethervpn:*:*:*:*:developer:*:*:* Versions up to 5.2.5188 Vulnerable ·SoftEther VPN

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-39312
  2. 2026-10-25 EPSS moved to the below the 50th percentile

References

Exploit 1

  • TI-2024-25755 SoftEther VPN with L2TP - 2.75x Amplification CVSS 3.1MEDIUM 5.3
  • TI-2025-23824 SoftEtherVPN Affected by NULL dereference in DeleteIPv6DefaultRouterInRA CVSS 3.1LOW 3.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences