CVE-2025-66286: WebKitGTK/WPE WebKit SSRF Vulnerability

CVE-2025-66286 Overview

An API design flaw has been identified in WebKitGTK and WPE WebKit that allows untrusted web content to unexpectedly perform IP connections, DNS lookups, and HTTP requests. Applications that utilize the WebPage::send-request signal handler expect to have the ability to approve or reject all network requests. However, this vulnerability allows certain types of HTTP requests to bypass this signal handler entirely, undermining application-level network security controls.

Critical Impact

Untrusted web content can bypass application-level network request filtering, potentially enabling unauthorized data exfiltration, Server-Side Request Forgery (SSRF)-like behavior, or communication with attacker-controlled infrastructure without application awareness.

Affected Products

• WebKitGTK (affected versions not specified in advisory)
• WPE WebKit (affected versions not specified in advisory)
• Applications utilizing WebPage::send-request signal handler for network request filtering

Discovery Timeline

• 2026-04-23 - CVE-2025-66286 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-66286

Vulnerability Analysis

This vulnerability represents a classic Authorization Bypass flaw stemming from an API design issue (CWE-639: Authorization Bypass Through User-Controlled Key). The core problem lies in the inconsistent handling of network requests within the WebKit engine's internal architecture.

Applications embedding WebKitGTK or WPE WebKit often rely on the WebPage::send-request signal handler as a security boundary to intercept, inspect, and potentially block outgoing network requests from web content. This is a critical security mechanism for applications that need to enforce network policies, prevent data exfiltration, or restrict communication to authorized domains.

The vulnerability arises because certain categories of HTTP requests are processed through a code path that does not trigger this signal handler. As a result, malicious or untrusted web content can initiate network communications that the host application believes it has blocked or never authorized.

Root Cause

The root cause is an API design flaw where not all network request types are routed through the WebPage::send-request signal handler. This creates an inconsistency in the security model where applications assume complete visibility and control over network requests, but certain request types bypass this control mechanism entirely. The bypass likely occurs due to separate code paths handling different request types (such as prefetch, preconnect, or specific resource loading operations) that were not integrated with the signal handler architecture.

Attack Vector

An attacker can exploit this vulnerability by crafting web content that triggers the specific types of HTTP requests that bypass the WebPage::send-request signal handler. The attack is network-based and requires user interaction (such as visiting a malicious page or viewing attacker-controlled content within an application).

Potential attack scenarios include:

1. Data Exfiltration: Sensitive information visible to web content could be transmitted to attacker-controlled servers without the application detecting or blocking the request
2. Internal Network Reconnaissance: The bypassed requests could perform DNS lookups and IP connections to probe internal network infrastructure
3. Security Control Bypass: Applications using the signal handler for content security policies, ad blocking, or parental controls would have their filtering mechanisms circumvented

For detailed technical information about the specific request types that bypass the handler, refer to the WebKit Bug Report #259787.

Detection Methods for CVE-2025-66286

Indicators of Compromise

• Unexpected outbound network connections from applications embedding WebKitGTK or WPE WebKit
• DNS queries to suspicious or unknown domains originating from WebKit-based applications
• Network traffic to external endpoints that should have been blocked by application-level filtering
• Log entries showing HTTP requests that were not captured by WebPage::send-request handlers

Detection Strategies

• Implement network-level monitoring to detect outbound connections from WebKit-based applications independent of application-layer filtering
• Deploy endpoint detection rules to monitor for unusual network activity patterns from applications known to use WebKitGTK or WPE WebKit
• Use packet capture or network flow analysis to identify connections that bypass expected application security controls
• Audit application logs for discrepancies between expected filtered requests and actual network traffic

Monitoring Recommendations

• Enable network traffic logging at the firewall or proxy level for WebKit-based applications
• Implement egress filtering to restrict outbound connections to known-good destinations
• Monitor for DNS resolution of suspicious domains from application processes
• Configure SentinelOne Singularity Platform to alert on anomalous network behavior from affected applications

How to Mitigate CVE-2025-66286

Immediate Actions Required

• Identify all applications in your environment that embed WebKitGTK or WPE WebKit
• Review the Red Hat CVE Advisory for vendor-specific guidance and patch availability
• Implement network-level egress filtering as a defense-in-depth measure
• Consider restricting exposure of sensitive internal resources to WebKit-based applications until patched

Patch Information

Consult your distribution's security advisory channels for WebKitGTK and WPE WebKit updates. Red Hat users should monitor the Red Hat Bug Report #2424652 for patch release information. Apply vendor-provided security updates as soon as they become available for your specific distribution.

Workarounds

• Implement network-level filtering (firewall rules, proxy policies) to enforce egress controls independent of application-layer filtering
• Restrict WebKit-based applications from accessing sensitive internal network resources
• Use application sandboxing or containerization to limit network access capabilities
• Consider temporarily disabling features that load untrusted web content in critical applications until patches are applied

# Example: Restrict outbound connections for WebKit processes using iptables
# Adjust the allowed destinations as needed for your environment
iptables -A OUTPUT -m owner --cmd-owner "*webkit*" -d <allowed_destination> -j ACCEPT
iptables -A OUTPUT -m owner --cmd-owner "*webkit*" -j LOG --log-prefix "WEBKIT-BLOCKED: "
iptables -A OUTPUT -m owner --cmd-owner "*webkit*" -j DROP