RCE in Opnsense Core

CVE-2026-57155

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the Firewall Alias GeoIP importer's process_zip() and process_gzip() paths in src/opnsense/scripts/filter/lib/alias/geoip.py use an unvalidated CSV country_code value to construct output filenames below /usr/local/share/GeoIP/alias. A user with Firewall Alias Edit privilege can configure an attacker-controlled GeoIP source URL and supply an archive whose country code traverses into another existing directory, causing attacker-controlled content to be written as root with an -IPv4 or -IPv6 suffix. A crafted newsyslog fragment and oversized log file can use the default hourly root cron job to execute commands as root, resulting in complete firewall compromise. This issue is fixed in version 26.1.11.

Vulnerability class: Path Traversal (Directory Traversal)

Published .

CVSS v3 metric

CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-57155?
CVE-2026-57155 is a critical-severity vulnerability in Opnsense Core, classified under Path Traversal. CVSS score: 9.9/10. Published 2026-10-15.
How severe is CVE-2026-57155?
Critical severity. CVSS v3 base score is 9.9 out of 10.