CVE-2026-58393

What it is

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the OpenVPN Client Specific Override common_name field accepts path traversal sequences and openvpn_csc_conf_write() concatenates the value into /var/etc/openvpn-csc/<vpnid>/<common_name> without normalization or a basename check. The affected event handlers are client_connect.php and user_pass_verify.php. An authenticated user with Client Specific Override privileges can store the traversal value, and a matching OpenVPN client-connect or authentication event causes a generated CSO file to be written outside the intended directory. The file content is generated OpenVPN configuration rather than arbitrary bytes, and practical exploitation requires the attacker to cause a matching common name or username to be processed. This issue is fixed in version 26.1.11.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data tampering.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-06-30 18:19 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-10-15 16:18 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-10-15 21:08 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 5.9 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-10-15 16:18 UTC

Last modified

2026-10-15 21:08 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Deferred

Attack profile CVSS 3.1 · 5.9

Attack vector

Network

Complexity

High

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-58393.md and follow it. Check whether this project is affected by CVE-2026-58393. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge