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Fencer Intel
critical 9.9

CVE-2026-57155 json

OPNsense: Root RCE via Arbitrary File Write in GeoIP Alias Importer

published 4mo ago modified 27d ago also EUVD-2026-102114 , GHSA-wjqq-rfmm-v5h3

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository opnsense/core. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
9.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 58%
public exploits
0
none known

Summary

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.

Patch / fix

  • opnsense opnsense 26.1.11

Is CVE-2026-57155 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
27d ago

Exploit prediction

0.86% chance of exploitation in the next 30 days, higher than 58% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/opnsense/core/security/advisories/GHSA-wjqq-rfmm-v5h3 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

  • opnsense core

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-73 External Control of File Name or Path
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of opnsense/core published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.