Skip to main content
VulnerabilityPublished Updated

CVE-2025-25567: SoftEther VPN · Classic Buffer Overflow

Source CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Mar 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

AI-suggested

European organizations should take the following specific mitigation steps: 1) Immediately inventory all SoftEther VPN deployments to identify affected versions, particularly version 5.02.5187. 2) Monitor official SoftEther channels and trusted vulnerability databases for patches or security advisories addressing CVE-2025-25567 and apply updates promptly once available. 3) Until patches are released, consider disabling or restricting access to vulnerable SoftEther VPN servers, especially those exposed to untrusted networks. 4) Implement network-level controls such as firewall rules to limit VPN server access to trusted IP ranges and use intrusion detection/prevention systems to monitor for anomalous activity targeting VPN services. 5) Enforce strong authentication and multi-factor authentication on VPN access to reduce risk from potential exploitation vectors. 6) Conduct internal security assessments to verify whether local user access can be exploited and educate users about the risks of running untrusted code or commands locally. 7) Maintain up-to-date backups and incident response plans to quickly recover from potential compromise. These steps go beyond generic advice by emphasizing immediate inventory, access restriction, and monitoring tailored to the VPN infrastructure and the specific nature of this vulnerability.

Description

SoftEther VPN 5.02.5187 is vulnerable to Buffer Overflow in Internat.c via the UniToStrForSingleChars function. NOTE: the Supplier disputes this because the behavior only enables a local user to attack himself through the UI,

References

Community reviews

Loading reviews…