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CVE-2026-53581

CRITICALCVSS 9/10EPSS 0.47%

Last modified

CVE-2026-53581 is a critical-severity vulnerability rated 9/10 on the CVSS scale. 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. EPSS estimates a 0.47% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
9/10

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:L/A:H

EPSS Probability
0.47%

38.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
opnsensecore< 26.1.9; < 26.4_20

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

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.
How severe is CVE-2026-53581?
CVE-2026-53581 has a CVSS score of 9/10 (CRITICAL severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.
How do I fix CVE-2026-53581?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST