What is CVE-2023-38999?

CVE-2023-38999 is a medium-severity vulnerability in Opnsense, classified under Cross-Site Request Forgery (CSRF). CVSS score: 6.5/10. Published 2023-08-09.

How severe is CVE-2023-38999?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Is CVE-2023-38999 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

CSRF in Opnsense

CVE-2023-38999

A Cross-Site Request Forgery (CSRF) in the System Halt API (/system/halt) of OPNsense Community Edition before 23.7 and Business Edition before 23.4.2 allows attackers to cause a Denial of Service (DoS) via a crafted GET request.

Vulnerability class: CSRF (Cross-Site Request Forgery)

Published 2023-08-09 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.004 (31.4th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 31.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Opnsense

Weakness classification (CWE)

CWE-352 — Cross-Site Request Forgery (CSRF)

Public proof-of-concept exploits

References

github.com/opnsense/core/commit/5d68f43d1f254144831881fc87d885eed120cf3c (Patch)
logicaltrust.net/blog/2023/08/opnsense.html (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2023-38999?: CVE-2023-38999 is a medium-severity vulnerability in Opnsense, classified under Cross-Site Request Forgery (CSRF). CVSS score: 6.5/10. Published 2023-08-09.
How severe is CVE-2023-38999?: Medium severity. CVSS v3 base score is 6.5 out of 10.
Is CVE-2023-38999 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.