CVE-2026-11264: Content Security Policy Bypass in Chrome – Patch to 149.0.7827.53

Technical summary

The vulnerability resides in Chrome's Content Security Policy implementation (CWE-693: Improper Neutralization of Special Elements used in a Policy). A remote attacker can construct a specially crafted HTML document that causes Chrome to mishandle or fail to enforce CSP directives. The bypass is not a memory corruption or authentication flaw, but rather a logic error in policy validation. The attack vector is network-based with low attack complexity, requiring only user interaction (clicking a link, visiting a site). The Chromium security team rated this as Low severity in their internal assessment, though the CVSS 3.1 score of 4.3 reflects a Medium severity due to the integrity impact of allowing unauthorized content execution.

Business impact

Organizations relying on websites protected by CSP to prevent XSS attacks, data exfiltration, or malware injection face a degraded security posture for Chrome users running vulnerable versions. SaaS platforms, financial institutions, and any web property using CSP as a key defensive layer should treat this as a control weakness during the window before user patching. The impact is primarily on web application security rather than endpoint compromise; however, it can facilitate credential theft or session hijacking if an attacker chains this with social engineering or malicious ad injection.

Affected systems

Google Chrome prior to version 149.0.7827.53 is directly affected. The vulnerability also impacts Apple macOS, Microsoft Windows, and Linux systems that run vulnerable Chrome versions, since Chrome is cross-platform. Organizations should inventory Chrome deployments across all operating systems in their environment. Chromium-based browsers (Edge, Brave, Opera, etc.) derived from the same codebase may also be vulnerable depending on their release cycle and whether they have applied the corresponding patch.

Exploitability

Exploitability is moderate. The attack requires crafting a malicious HTML page and convincing or tricking a user into visiting it—either through phishing, malvertising, or compromised third-party content. There is no known public exploit code, and the vulnerability is not currently tracked in the CISA Known Exploited Vulnerabilities (KEV) catalog. However, the attack surface is large because any website an employee visits could potentially be compromised or weaponized. Once visited, no additional user action is required; the CSP bypass occurs passively.

Remediation

Update Google Chrome to version 149.0.7827.53 or later. Chrome typically auto-updates on most systems, but users should verify they are on the latest version via Chrome Settings > About Chrome. Organizations managing Chrome centrally (via MDM, Group Policy, or enterprise deployment) should push the patched version to all devices. No workarounds exist; patching is the only mitigation. For web administrators, review CSP policies to ensure defense-in-depth; do not rely solely on CSP during the remediation window.

Patch guidance

Chrome 149.0.7827.53 and subsequent releases contain the fix for this CSP bypass. Verify the patch version in your deployment against the official Chrome release notes published after June 5, 2026. For enterprise environments, test the patch in a limited pilot before full rollout to confirm no regressions with internal applications. Note that this patch also includes fixes for other security issues; review the full advisory to understand the complete security updates bundled in the release.

Detection guidance

Monitor network logs and web server logs for signs of CSP bypass attempts: look for requests that violate expected CSP policies but were allowed to succeed, or unusual cross-origin requests that should have been blocked. Browser telemetry and security event logs may show CSP violations that were not properly blocked. However, passive detection is limited because the vulnerability manifests as a logic flaw rather than a crash or error. Endpoint detection tools should focus on ensuring Chrome version compliance; organizations can audit installed Chrome versions via MDM or script-based scanning. Consider blocking or warning on untrusted external websites if CSP protection is critical for your infrastructure.

Why prioritize this

This vulnerability should be prioritized as Medium-High for urgent patching despite its modest CVSS score. Reason: (1) CSP is a foundational web security control; bypassing it weakens multiple downstream defenses; (2) the attack surface is large and user-initiated, making it difficult to defend against at the perimeter; (3) Chrome is ubiquitous in corporate and consumer environments; (4) the vulnerability is unpatched in millions of instances. While not in KEV and rated Low severity by Chromium, the breadth of affected systems and the attack vector justify aggressive patching within 7–14 days.

Risk score, explained

The CVSS 3.1 score of 4.3 (Medium) reflects: Network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requires user interaction (UI:R). The impact is limited to integrity (I:L)—allowing unintended content execution—with no confidentiality or availability impact. The low Chromium severity rating acknowledges that the vulnerability does not directly compromise the browser or enable remote code execution. However, the real-world risk is elevated due to the prevalence of Chrome, the fundamental nature of CSP as a security control, and the ease with which social engineering can drive users to malicious pages. Organizations should weigh the CVSS score alongside business context.

Frequently asked questions