CVE-2026-111664 in Portmaster
Summary
by MITRE • 10/16/2026
Safing Portmaster before 2.2.5 contains a missing authorization vulnerability that allows unprivileged local processes to force updates by calling the POST /api/v1/updates/from-url endpoint registered with api.PermitAnyone. Attackers can supply an attacker-controlled index URL that bypasses version checks and auto-apply settings, installing older Safing-signed releases carrying previously fixed vulnerabilities.
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Analysis
by VulDB Data Team • 10/16/2026
The vulnerability identified in Safing Portmaster versions prior to 2.2.5 represents a critical failure in access control mechanisms within the application's local API interface. Specifically, the endpoint POST /api/v1/updates/from-url was registered with an authorization level designated as api.PermitAnyone. This configuration effectively grants unrestricted write access to any process running on the same user context or system where Portmaster is installed, regardless of whether that process possesses administrative privileges or standard user rights. In a typical secure architecture, endpoints responsible for modifying application state, particularly those involving software updates and security configurations, must enforce strict authentication and authorization checks to ensure that only trusted entities can initiate such changes. The absence of these controls creates a significant attack surface for local privilege escalation and integrity compromise attacks.
From a technical perspective, the flaw allows an unprivileged attacker or malicious process on the same host to interact directly with the Portmaster API without providing valid credentials. By invoking the specified endpoint, the attacker can supply a custom index URL that points to a repository controlled by the adversary. This capability bypasses the standard version verification logic and auto-apply settings mechanisms built into the update system. Consequently, the application is coerced into downloading and installing software packages from an untrusted source. The most severe aspect of this exploitation vector is the ability to force the installation of older Safing-signed releases that contain previously patched vulnerabilities. Since these older versions are cryptographically signed by Safing itself, they pass standard integrity checks, allowing malicious code or known exploit vectors embedded in those legacy builds to execute with the elevated privileges associated with the Portmaster service.
The operational impact of this vulnerability is substantial, as it undermines both the confidentiality and integrity guarantees provided by the security tool itself. An attacker leveraging this flaw can effectively neutralize the protective measures offered by Safing Portmaster by downgrading its version or injecting malicious updates that re-introduce known weaknesses such as cross-site scripting, remote code execution flaws, or data exfiltration capabilities previously addressed in newer releases. This scenario aligns with CWE-862, which describes missing authorization issues where a user lacks permissions for an action they are able to perform. Furthermore, the exploitation technique maps directly to MITRE ATT&CK tactic T1059, specifically sub-technique T1059.007 regarding command and script interpretation via local APIs or scripts, as well as T1484.002 for domain policy modification if configuration settings are altered during the update process. The ability to force updates also relates to supply chain integrity concerns, although in this context, it is a direct local exploitation rather than an external third-party compromise.
To mitigate this vulnerability and restore secure operation, immediate action must be taken by upgrading Safing Portmaster to version 2.2.5 or later, where the authorization controls for API endpoints have been corrected. Until such an upgrade can be performed, system administrators should restrict local network access to the Portmaster API interface using firewall rules that limit connections to localhost only if remote management is not required, although this does not fully mitigate local process attacks. Additionally, implementing strict application whitelisting and monitoring tools for unexpected changes in update directories or configuration files can help detect exploitation attempts. It is also advisable to audit system logs for unusual POST requests directed at the Portmaster API endpoints from non-system processes. Ensuring that all software components are kept up-to-date with vendor-recommended patches remains the primary defense against such authorization bypass vulnerabilities, as they often serve as entry points for more complex multi-stage attacks targeting local privilege escalation and persistent access establishment.