OpenVPN 2 (Community): Divide By Zero
CVE-2023-46849 is a high-severity divide by zero vulnerability in OpenVPN 2 (Community) from OpenVPN, 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 OpenVPN 2 (Community) versions: 2.6.0 through 2.6.6. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.36% chance of exploitation within 30 days, higher than 72% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of OpenVPN 2 (Community) you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on community.openvpn.net for workarounds and exact fixed builds.
- 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 |
|---|---|---|---|
| OpenVPN | OpenVPN 2 (Community) | 2.6.0 through 2.6.6 | Not stated |
| OpenVPN | Access Server | 2.11.0 through 2.11.3; 2.12.0 through 2.12.1 | Not stated |
| Openvpn | Openvpn | 2.6.0 through 2.6.6 | Not stated |
| Openvpn | Openvpn Access Server | 2.11.0 through 2.11.3; 2.12.0; 2.12.1 | Not stated |
| Debian | Debian Linux | 12.0 | Not stated |
| Fedora Project | Fedora | 39 | 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 | NVD |
| CVSS 3.1 | 7.5 | High | CISA (ADP) |
Official description
Using the --fragment option in certain configuration setups OpenVPN version 2.6.0 to 2.6.6 allows an attacker to trigger a divide by zero behaviour which could cause an application crash, leading to a denial of service.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Divide By Zero
The product divides a value by zero.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- debian.org/security/2023/dsa-5555Third Party Advisory
Other references
Other vulnerabilities in OpenVPN 2 (Community)
- 9.8 Critical severity
Recent Divide By Zero vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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