CVE-2026-13876: Chrome Content Security Policy Bypass via Network Interception

Technical summary

This vulnerability stems from an inappropriate implementation in Chrome's Network layer that fails to properly enforce Content Security Policy directives when processing malicious network traffic. The flaw is classified under CWE-693 (Protection Mechanism Failure), indicating a breakdown in a security control rather than a direct injection or parsing flaw. An attacker with a privileged network position—such as control over a local network segment, ISP-level access, or a compromised proxy—can craft network traffic that causes the browser to disregard CSP headers or policies the website intended to enforce. The browser requires user interaction to trigger the vulnerability, suggesting the attacker must induce the user to navigate to a target site or click a malicious link within the context of the compromised network. The CVSS 3.1 score of 6.5 reflects the combination of network-level attack surface, no authentication required, low complexity, user interaction requirement, and integrity impact (ability to inject content) without confidentiality or availability impact.

Business impact

For enterprise environments, this vulnerability represents a network-layer risk rather than a browser-only issue. Organizations with adequate network monitoring and segmentation may face lower exposure. However, for users on untrusted or shared networks (coffee shops, hotels, public Wi-Fi), the ability to bypass CSP creates a window for injection attacks that could lead to credential theft, malware delivery, or session hijacking if combined with other web attack techniques. For Chrome-dependent workflows, organizations should prioritize patch deployment to reduce the window of exposure, particularly for users who frequently work on open networks. The impact is contained to integrity—no direct data exfiltration or system compromise—but can facilitate secondary attacks.

Affected systems

Google Chrome versions prior to 150.0.7871.47 are affected. This includes stable, extended, and legacy release channels running earlier versions. The vulnerability does not affect Chromium-based browsers unless they have backported the same vulnerable code path. Users should verify their current Chrome version (Settings > About Chrome) and ensure automatic updates are enabled. Organizations using managed Chrome instances should verify patch deployment to 150.0.7871.47 or later.

Exploitability

Exploitation requires a privileged network position, meaning the attacker must be able to observe, modify, or redirect network traffic. This could be achieved through ARP spoofing on a local network, BGP hijacking at ISP scale, compromised proxy servers, or man-in-the-middle positioning on a shared Wi-Fi network. Importantly, the attacker cannot exploit this through a simple malicious website; they must actively interfere with network communications. User interaction is required, indicating the victim must visit a website while the attacker maintains the network position and is actively injecting traffic. The barrier to exploitation is moderate—it is not a one-click remote code execution, but organized attackers or state actors with network infrastructure access could carry out such attacks at scale. Casual attackers would find this difficult. The vulnerability is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, suggesting active exploitation has not been reported at the time of publication.

Remediation

Update Google Chrome to version 150.0.7871.47 or later. Chrome users with automatic updates enabled will receive this patch automatically; verify completion by navigating to Settings > About Chrome. For enterprise environments, deploy the patch through your configuration management system and verify rollout using Chrome enterprise policies or mobile device management (MDM) tools. No workarounds exist; patching is the only effective mitigation. Organizations concerned about network-level attacks should complement the patch with network segmentation, VPN enforcement for users on untrusted networks, and HSTS preloading for critical sites to reduce the attack surface.

Patch guidance

The patch is available in Chrome 150.0.7871.47. Verify the version in Settings > About Chrome; the browser will check for updates automatically and install them on next restart. For enterprise deployments: confirm your Chrome release channel and push the update through your MDM or Group Policy distribution mechanism. Test on a subset of devices before full rollout if your environment requires validation. Note that older Chrome versions (those on the extended support channel) should also be updated; check Google's official security advisory for guidance specific to extended support timelines. The patch does not require any configuration changes—it is a drop-in replacement.

Detection guidance

End-point detection is limited because the vulnerability requires active network interception; you cannot detect exploitation by observing Chrome process behavior alone. However, organizations can improve network visibility by: (1) Monitoring for ARP spoofing, DHCP snooping violations, or unexpected proxy injection on managed networks; (2) Using certificate pinning or HPKP headers on sensitive internal sites to detect man-in-the-middle attempts; (3) Analyzing DNS and TLS logs for unexplained redirects or certificate mismatches; (4) Deploying network intrusion detection systems (IDS) that flag suspicious traffic patterns. At the browser level, you can audit CSP policy compliance by reviewing Security tab warnings in Chrome DevTools. For forensics: if you suspect exploitation, review network packet captures for injected content and correlate with browser history and page source artifacts.

Why prioritize this

This vulnerability merits prompt patching due to its potential to enable secondary attacks despite the requirement for network-level access. Organizations should prioritize it as a medium-priority patch, staging deployment within 1-2 weeks. The patch is low-risk (it is a security fix with no known breaking changes), making it safe to deploy broadly. Highest priority should go to users who work on untrusted networks (remote workers, mobile staff, contractors), followed by general office-based users. The vulnerability's absence from the KEV catalog suggests it has not been exploited at scale in the wild, providing a window of opportunity to patch proactively before it becomes a target.

Risk score, explained

The CVSS 3.1 score of 6.5 (MEDIUM) reflects a network-accessible vulnerability that requires attacker positioning, no authentication, low attack complexity, user interaction, and integrity impact only. The network requirement (AV:N) and lack of privileges or authentication (PR:N, AU:N) elevate the score, but the requirement for user interaction (UI:R) and the absence of confidentiality or availability impact lower it. This score appropriately captures a vulnerability that is non-trivial to exploit but poses a real risk in high-risk network scenarios (public Wi-Fi, compromised ISP links). It does not reach HIGH or CRITICAL thresholds because active network control and user action are both required, and the impact is limited to integrity (content injection) rather than system compromise.

Frequently asked questions