CVE-2026-111232 in pfSense CE
Summary
by MITRE • 10/15/2026
Netgate pfSense CE 2.3.0 through 2.9.0 contains a stored cross-site scripting vulnerability that allows authenticated users with Firewall: Rules or NAT: Port Forward privileges to inject scripts via the separator color field. Attackers can submit a crafted separator[] color value that display_separator() renders unencoded into class attributes, executing in administrators' browsers to perform WebGUI actions with their privileges.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified within Netgate pfSense Community Edition versions 2.3.0 through 2.9.0 represents a significant security flaw classified as a stored cross-site scripting issue. This specific type of vulnerability arises when an application stores malicious script content in its database or persistent storage and subsequently renders that content without proper validation or encoding, leading to execution within the context of other users' browsers. In this particular case, the attack vector is tied directly to the administrative interface's configuration capabilities, specifically targeting fields related to visual customization such as separator colors. The presence of this flaw indicates a failure in input sanitization mechanisms where user-supplied data intended for aesthetic purposes is treated as executable code rather than plain text during rendering processes.
The technical root cause lies in how the pfSense WebGUI handles the display_separator function when processing color values submitted by authenticated users. When an administrator with privileges to manage Firewall Rules or NAT Port Forward configurations submits a crafted value into the separator field, the system fails to encode special characters such as angle brackets and quotation marks before inserting them into HTML class attributes. This lack of output encoding allows attackers to inject arbitrary JavaScript code that becomes part of the page structure. Because pfSense is an enterprise-grade firewall solution often deployed in critical network infrastructure environments, the WebGUI serves as a primary management interface where high-privilege actions are routinely performed, making any compromise of this session highly consequential for overall system integrity and confidentiality.
From an operational perspective, the impact of this vulnerability extends beyond simple script execution to include full administrative takeover under certain conditions. An attacker who successfully exploits this flaw can execute JavaScript commands within the victim administrator's browser context, effectively impersonating that user during their active session. This capability enables the modification of firewall rules, alteration of network address translation settings, and potentially the exfiltration of sensitive configuration data or credentials stored in local storage cookies. The persistent nature of stored XSS means that once a malicious payload is injected by an attacker with write access to these specific fields, it remains active until manually removed, posing a continuous threat to any administrator who accesses the interface thereafter. This persistence amplifies the risk significantly compared to reflected variants which require immediate user interaction for each execution attempt.
In terms of industry standard classifications, this vulnerability aligns closely with CWE-79 Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting and specifically falls under stored XSS scenarios where data is retained in server-side storage before being served to clients. Furthermore, the exploitation technique maps directly to MITRE ATT&CK techniques involving Client-Side Injection for code execution and potentially Credential Access if session tokens or cookies are harvested through DOM manipulation events. The requirement for authentication with specific privileges such as Firewall Rules management places this within the context of privilege escalation pathways where lower-level access is leveraged to achieve higher levels of control over network security appliances.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. Administrators should immediately apply vendor-provided patches that update pfSense CE to versions beyond 2.9.0 or later releases containing fixes for this specific input validation gap. Until patching is feasible, restricting access to the WebGUI via IP whitelisting can reduce exposure by limiting which source addresses are permitted to interact with administrative endpoints. Additionally implementing strict Content Security Policy headers within the web server configuration may help mitigate some effects of script execution even if injection occurs, although this serves as a compensating control rather than a fix for the underlying code defect. Future development cycles should enforce rigorous input validation and output encoding standards across all form fields to prevent similar vulnerabilities from emerging in other modules of the management interface ensuring robust defense-in-depth practices are maintained throughout the application lifecycle.