CVE-2023-22308Public exploitNetwork attack vector

Unauthenticated server crash via OpenVPN length wraparound

Published Oct 12, 2023 · Updated Aug 2, 2024

Integer underflow in SoftEther VPN 5.01.9674 and 5.02 allows remote attackers to crash vpnserver with a crafted OpenVPN TCP packet. In OvsProcessData, adding the two-byte header to a 65,535-byte payload length wraps packet_size to one, but Clone still copies 65,535 bytes from the stack buffer. Unauthenticated network reachability to an enabled OpenVPN listener is sufficient, and the demonstrated consequence is vpnserver termination.

CVSS severity7.5
High
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer underflow in SoftEther VPN 5.01.9674 and 5.02 allows remote attackers to crash vpnserver with a crafted OpenVPN TCP packet. In OvsProcessData, adding the two-byte header to a 65,535-byte payload length wraps packet_size to one, but Clone still copies 65,535 bytes from the stack buffer. Unauthenticated network reachability to an enabled OpenVPN listener is sufficient, and the demonstrated consequence is vpnserver termination.

The record

CVE
CVE-2023-22308
Published
Oct 12, 2023
Updated
Aug 2, 2024
Vendor
SoftEther VPN Project
Product
SoftEther VPN
Classifications
CWE-191, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 12, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.01.9674
  2. Affected versionversion=5.02

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SoftEther VPN Project · SoftEther VPNversion=5.01.9674; version=5.02

Published CVSS scores

7.5Cisco TalosCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-191Integer Underflow (Wrap or Wraparound)
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

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Technologies

Your stack

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Your stack

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