What is CVE-2026-53581?
OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.9 of opnsense/core and version 26.4_20 of BE/opnsense/core, a path traversal vulnerability in the NTP configuration module allows an attacker to overwrite arbitrary files on the system as the root user. By manipulating the GPS or PPS serial port parameter, an attacker with access to the NTP configuration can escape the intended directory and force the system to write user-controlled data to any file on the filesystem. Version 26.1.9 of opnsense/core and version 26.4_20 of BE/opnsense/core patch the issue.
The record classifies CVE-2026-53581 under weakness classes CWE-22, CWE-73. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs high-privilege credentials, needs no user interaction, and has high impact on confidentiality, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 27 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:L/A:H - EPSS (FIRST)
- 0.3% probability of exploitation in the next 30 days, higher than 25.4% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 5.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-09-08
Is CVE-2026-53581 being exploited?
It currently carries a trending score of 36 in the Threadlinqs vulnerability feed.
Affected products and versions
- opnsense: core
How to fix CVE-2026-53581
No vendor patch reference has been recorded for CVE-2026-53581 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-53581
No threat campaign in the Threadlinqs corpus currently references CVE-2026-53581, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.
Sources
Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.