CyberSecBulletin
CVE-2023-32634NVD status: Modified

SoftEther VPN: Channel Accessible by Non-Endpoint

Published Updated By the CyberSecBulletin desk

CVE-2023-32634 is a high-severity channel accessible by non-endpoint vulnerability in SoftEther VPN, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, without any action from a user. Affected SoftEther VPN versions: 4.41-9782-beta; 5.01.9674. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.43% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of SoftEther VPN you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on softether.org for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
SoftEther VPNSoftEther VPN4.41-9782-beta; 5.01.9674Not stated
Softethervpn4.41-9782; 5.01.9674Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA (cisco.com)
CVSS 3.17.4HighNVD

Official description

An authentication bypass vulnerability exists in the CiRpcServerThread() functionality of SoftEther VPN 5.01.9674 and 4.41-9782-beta. An attacker can perform a local man-in-the-middle attack to trigger this vulnerability.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Channel Accessible by Non-Endpoint

The product does not adequately verify the identity of actors at both ends of a communication channel, or does not adequately ensure the integrity of the channel, in a way that allows the channel to be accessed or influenced by an actor that is not an endpoint.

How developers prevent this class of flaw

  • In order to establish secure communication between two parties, it is often important to adequately verify the identity of entities at each end of the communication channel. Always fully authenticate both ends of any communications channel.
  • Adhere to the principle of complete mediation.
  • A certificate binds an identity to a cryptographic key to authenticate a communicating party. Often, the certificate takes the encrypted form of the hash of the identity of the subject, the public key, and information such as time of issue or expiration using the issuer's private key. The certificate can be validated by deciphering the certificate with the issuer's public key. See also X.509 certificate signature chains and the PGP certification structure.

More Channel Accessible by Non-Endpoint vulnerabilities (CWE-300)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Technical write-ups (may include proof of concept)

Other vulnerabilities in SoftEther VPN

All SoftEther VPN vulnerabilities

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