Root file overwrite on a widely deployed firewall product enabling RCE/persistence; high-impact on network infrastructure; patches released.
CVE-2026-53581
OPNsense NTP module path traversal allows root file overwrite
Is CVE-2026-53581 being exploited?
Not confirmed. CVE-2026-53581 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.33% probability of exploitation in the next 30 days.
How severe is CVE-2026-53581?
CVE-2026-53581 is rated Critical with a CVSS score of 9.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-53581?
Yes. A fix has been recorded for CVE-2026-53581. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-53581 affect?
CVE-2026-53581 affects OPNsense core < 26.1.9, BE/opnsense/core < 26.4_20, OPNsense firewall deployments. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-53581?
Upgrade to opnsense/core 26.1.9 or BE/opnsense/core 26.4_20 immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Arbitrary file overwrite as root via NTP config path traversal, enabling remote code execution, persistence, or full system compromise.
Immediate action required
- affected< 26.1.9
- affected< 26.4_20
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.