CVE-2026-11276: Google Chrome Auth Bypass Vulnerability

CVE-2026-11276 Overview

CVE-2026-11276 affects Google Chrome versions prior to 149.0.7827.53. The vulnerability stems from an inappropriate implementation in the Cast component, which handles media streaming to compatible receiver devices. An attacker positioned on the same local network segment can send malicious network traffic to bypass discretionary access control on a target system running a vulnerable Chrome browser. Chromium classifies the security severity as Low, and the issue maps to [CWE-269] Improper Privilege Management. The flaw impacts Chrome on Windows, macOS, and Linux desktop platforms.

Critical Impact
An adjacent attacker on the local network can bypass access controls enforced by the Chrome Cast feature, enabling limited unauthorized interaction with the victim browser without user interaction.

Affected Products

Google Chrome prior to 149.0.7827.53
Microsoft Windows desktop installations of Chrome
Apple macOS and Linux desktop installations of Chrome

Discovery Timeline

2026-06-05 - CVE-2026-11276 published to the National Vulnerability Database (NVD)
2026-06-05 - Google publishes the Stable Channel update advisory
2026-06-05 - Last updated in NVD database

Technical Details for CVE-2026-11276

Vulnerability Analysis

The vulnerability resides in Chrome's Cast subsystem, which discovers and communicates with media receivers such as Chromecast devices over the local network. Cast relies on local network protocols including mDNS and DIAL for device discovery and session establishment. The inappropriate implementation fails to correctly enforce discretionary access control (DAC) when processing inbound network traffic intended for the Cast service. An attacker on the same broadcast domain can craft network traffic that the Cast component accepts and processes without applying expected access checks. The result is limited unauthorized influence over Cast operations, which can expose data or alter state that should require explicit user authorization. Successful exploitation requires no privileges and no user interaction, but the attacker must have local network adjacency to the victim. Confidentiality and integrity impacts are both rated low, and availability is not affected.

Root Cause

The Chromium issue tracker entry attributes the defect to missing or insufficient permission enforcement within the Cast code path. The component trusts certain network-originated requests on the assumption that the local segment is a trust boundary, which it is not in shared LAN, guest Wi-Fi, or compromised network environments. This mapping to [CWE-269] reflects the failure to constrain operations to users who possess the proper privileges. See the Chromium Issue Tracker Entry for technical context.

Attack Vector

Exploitation requires the attacker to reside on the same local network segment as the victim. The attacker transmits malicious network traffic targeting the Cast discovery or session endpoints exposed by the victim's Chrome process. Because no authentication or user prompt gates the malicious request, the bypass succeeds silently. Remote exploitation across routed networks is not possible without an intermediate foothold inside the broadcast domain.

No public proof-of-concept code is available. The vulnerability is described in prose by the vendor without exploitation details. Refer to the Google Chrome Update Blog for official remediation guidance.

Detection Methods for CVE-2026-11276

Indicators of Compromise

Unexpected mDNS or DIAL traffic originating from untrusted hosts on the local network segment targeting Chrome Cast service ports.
Chrome processes initiating Cast sessions or device pairings that do not correlate with user activity.
Anomalous discovery responses advertising rogue Cast receivers on corporate or guest networks.

Detection Strategies

Monitor endpoint Chrome versions through software inventory tooling and flag installations below 149.0.7827.53.
Inspect local network traffic for malformed or unauthorized Cast protocol exchanges using IDS signatures tuned to mDNS and DIAL anomalies.
Correlate browser process telemetry with network connections to identify Cast activity initiated without corresponding user interaction.

Monitoring Recommendations

Audit guest, BYOD, and IoT VLANs for unexpected devices advertising Cast receiver capabilities.
Track Chrome auto-update status across the fleet and alert on stalled or disabled update channels.
Log and review browser-originated multicast traffic in environments where Cast functionality is not required.

How to Mitigate CVE-2026-11276

Immediate Actions Required

Update Google Chrome to version 149.0.7827.53 or later on all Windows, macOS, and Linux endpoints.
Verify that Chrome auto-update is enabled and functioning by checking chrome://settings/help on representative endpoints.
Restart Chrome after the update to ensure the patched binaries are loaded into running processes.

Patch Information

Google released the fix in the Stable Channel update detailed in the Google Chrome Update Blog. Enterprise administrators distributing Chrome through MSI, MDM, or package managers should promote the fixed build to all managed endpoints. The corresponding Chromium issue is tracked at Chromium Issue 501780338.

Workarounds

Disable Cast functionality through enterprise policy using the EnableMediaRouter setting set to false where Cast is not required.
Segment user endpoints away from untrusted devices using VLANs and wireless client isolation to remove local network adjacency.
Block multicast traffic from guest networks reaching corporate endpoints at the switch or wireless controller level.

bash

# Configuration example: disable Chrome Media Router via enterprise policy
# Windows (registry)
reg add "HKLM\SOFTWARE\Policies\Google\Chrome" /v EnableMediaRouter /t REG_DWORD /d 0 /f

# macOS (plist)
defaults write com.google.Chrome EnableMediaRouter -bool false

# Linux (managed policy JSON at /etc/opt/chrome/policies/managed/)
# {
#   "EnableMediaRouter": false
# }