SoftEther VPN: Integer Underflow (Wrap or Wraparound)
CVE-2023-22308 is a high-severity integer underflow (wrap or wraparound) vulnerability in SoftEther VPN, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected SoftEther VPN versions: 5.01.9674; 5.02. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.84% chance of exploitation within 30 days, higher than 58% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of SoftEther VPN you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| SoftEther VPN | SoftEther VPN | 5.01.9674; 5.02 | Not stated |
| Softether | VPN | 5.01.9674; 5.02 | Not 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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- 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
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (cisco.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
An integer underflow vulnerability exists in the vpnserver OvsProcessData functionality of SoftEther VPN 5.01.9674 and 5.02. A specially crafted network packet can lead to denial of service. An attacker can send a malicious packet to trigger this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Underflow (Wrap or Wraparound)
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Technical write-ups (may include proof of concept)
- talosintelligence.com/vulnerability_reports/TALOS-2023-1737Exploit, Third Party Advisory
Other references
Other vulnerabilities in SoftEther VPN
- 7.4 High severity
- 7.8 High severity
- 8.1 High severity
- 7.5 High severity
- 7.5 High severity
Recent Integer Underflow (Wrap or Wraparound) vulnerabilities
- 7.5 High severity
- 8.1 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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