CVE-2023-27516Network attack vector

Unauthenticated client control via blank-password RPC

Published Oct 12, 2023 · Updated Aug 2, 2024

Authentication bypass in SoftEther VPN Client 4.41-9782-beta and 5.01.9674 allows remote attackers to control the client over TCP RPC. CiRpcAccepted accepts a password value matching the stored representation of a blank administrator password, then permits management RPCs instead of rejecting remote empty-password sessions. The flaw is reachable only when remote administration is enabled, the administrator password remains blank, and the TCP RPC listener is exposed; a successful connection grants unrestricted client configuration and operation.

CVSS severity7.3
High
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in SoftEther VPN Client 4.41-9782-beta and 5.01.9674 allows remote attackers to control the client over TCP RPC. CiRpcAccepted accepts a password value matching the stored representation of a blank administrator password, then permits management RPCs instead of rejecting remote empty-password sessions. The flaw is reachable only when remote administration is enabled, the administrator password remains blank, and the TCP RPC listener is exposed; a successful connection grants unrestricted client configuration and operation.

The record

CVE
CVE-2023-27516
Published
Oct 12, 2023
Updated
Aug 2, 2024
Vendor
SoftEther VPN Project
Product
SoftEther VPN
Classifications
CWE-453, T1133
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=4.41-9782
  2. Affected versionversion=4.41-9782-beta
  3. Affected versionversion=5.01.9674

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SoftEther VPN Project · SoftEther VPNversion=4.41-9782; version=4.41-9782-beta; version=5.01.9674

Published CVSS scores

7.0SoftEther VPN ProjectCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:L
7.3Cisco TalosCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-453Insecure Default Variable Initialization
T1133External Remote Services

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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