CVE-2026-13876: Google Chrome Auth Bypass Vulnerability

CVE-2026-13876 Overview

CVE-2026-13876 is a Content Security Policy (CSP) bypass vulnerability in the Network component of Google Chrome. The flaw affects Chrome versions prior to 150.0.7871.47 and stems from an inappropriate implementation that fails to enforce CSP directives correctly against certain network traffic. An attacker in a privileged network position can inject or manipulate traffic to bypass CSP protections. Successful exploitation undermines a key browser defense-in-depth control that restricts script sources, framing, and other content behaviors. Google classifies the Chromium security severity as Medium. The vulnerability requires user interaction, such as visiting an attacker-influenced page, and does not directly disclose data or crash the browser.

Critical Impact
Attackers positioned on the network path can bypass Content Security Policy in Chrome, weakening protections against script injection and content-based attacks on affected browsing sessions.

Affected Products

Google Chrome versions prior to 150.0.7871.47
Chromium-based browsers inheriting the vulnerable network stack
Desktop Chrome Stable channel across supported platforms

Discovery Timeline

2026-06-30 - CVE-2026-13876 published to NVD
2026-07-02 - Last updated in NVD database

Technical Details for CVE-2026-13876

Vulnerability Analysis

The vulnerability resides in Chrome's Network component and involves incorrect enforcement of Content Security Policy [CWE-693: Protection Mechanism Failure]. CSP is a browser security control that restricts which origins can load scripts, frames, images, and other resources into a page. When Chrome processes certain network responses, the implementation does not consistently apply CSP directives before the content reaches the rendering pipeline. An attacker who can observe or modify network traffic can craft responses that slip past CSP checks. The result allows unauthorized content to execute or load in contexts where CSP should have blocked it. This weakens site-defined protections against cross-site scripting, clickjacking, and mixed content risks. Users on hostile networks such as public Wi-Fi, compromised routers, or malicious upstream proxies are the primary targets.

Root Cause

The root cause is an inappropriate implementation in how Chrome's network stack coordinates with the CSP enforcement layer. Specific processing paths fail to apply the policy check consistently, creating a gap between policy declaration and policy enforcement. The Chromium issue tracker entry documents the internal fix.

Attack Vector

Exploitation requires network-adjacent access and user interaction. The attacker intercepts or modifies HTTP responses to a target site the victim visits. Because the CSP check is skipped for the crafted traffic, the injected content executes within the origin's security context. See the Chromium Issue Tracker Entry for additional technical detail.

No public proof-of-concept is available, and code-level exploitation details have not been released. Refer to the Google Chrome Stable Update for vendor advisory information.

Detection Methods for CVE-2026-13876

Indicators of Compromise

Chrome browser processes running versions below 150.0.7871.47 in enterprise inventory
Unexpected script or iframe loads from origins that should be blocked by a site's declared CSP
CSP violation reports missing for content that is nonetheless rendered
Anomalous man-in-the-middle indicators such as unexpected TLS certificate changes or downgraded HTTPS sessions

Detection Strategies

Inventory installed Chrome versions across managed endpoints and flag hosts below the patched build
Monitor CSP report endpoints for gaps or inconsistencies compared to expected violation patterns
Correlate browser telemetry with network events indicating proxy interception or certificate anomalies
Alert on Chrome executions from users connected to untrusted networks without VPN enforcement

Monitoring Recommendations

Ingest Chrome version telemetry into a centralized data lake for continuous compliance reporting
Track network-layer anomalies such as unexpected redirects, mixed content, and TLS interception attempts
Review browser update posture weekly and after each Chrome stable channel release

How to Mitigate CVE-2026-13876

Immediate Actions Required

Update Google Chrome to version 150.0.7871.47 or later on all managed endpoints
Restart Chrome after the update to ensure the patched network stack is loaded
Enforce automatic updates through group policy or MDM to prevent version drift
Require VPN or Zero Trust network access for users on untrusted networks

Patch Information

Google released the fix in the Chrome Stable channel update documented at the Google Chrome Stable Update. Upgrade to Chrome 150.0.7871.47 or later. Chromium-based browsers should apply their vendor's corresponding update once available.

Workarounds

Route browser traffic through trusted encrypted tunnels such as corporate VPN or SASE gateways
Enforce HTTPS-only mode in Chrome to reduce exposure to plaintext response manipulation
Restrict use of untrusted networks for sessions involving sensitive web applications until patching completes

bash

# Verify installed Chrome version on Windows, macOS, and Linux
# Windows
reg query "HKLM\SOFTWARE\Google\Update\Clients\{8A69D345-D564-463C-AFF1-A69D9E530F96}" /v pv

# macOS
defaults read /Applications/Google\ Chrome.app/Contents/Info CFBundleShortVersionString

# Linux
google-chrome --version