Deserialization in Pfrest Pfsense-Pkg-Restapi

CVE-2026-113779

The pfSense REST API package is an unofficial, open-source REST and GraphQL API for pfSense CE and pfSense Plus firewalls. A privilege escalation vulnerability in pfSense-pkg-RESTAPI prior to version 2.9.0 allows authenticated accounts holding the dedicated settings sync permission to modify REST API configuration secrets. This enables a non-administrative user to elevate their privileges to a full administrator. pfSense-pkg-RESTAPI 2.9.0 patches the issue. Access to the HA settings sync endpoint now strictly requires full administrative privileges (`page-all`). The sub-administrative sync privilege has been removed in versions v2.9.0 and later. In addition to correcting the access control boundary, version 2.9.0 includes the following hardening measures: opt-in default and format and validation modernization. As a workaround, one may mitigate exposure by taking either or all of the following steps. Revoke Scoped Permissions: Remove the `api-v2-system-restapi-settings-sync-post` privilege from all non-administrative users. Apply ACLs: Configure REST API Access Control Lists (ACLs) and/or firewall rules to restrict access to API endpoints exclusively to trusted administrator and HA peer IP addresses.

Vulnerability class: Insecure Deserialization

Published 2026-10-21 · last modified 2026-10-21.