CVE-2026-12453: Google Chrome Auth Bypass Vulnerability

CVE-2026-12453 Overview

CVE-2026-12453 is an input validation vulnerability [CWE-20] in the Input component of Google Chrome versions prior to 149.0.7827.155. The flaw allows a remote attacker who has already compromised the renderer process to bypass the same-origin policy through a crafted HTML page. Google rates the Chromium security severity as High, while the NVD assigns a CVSS v3.1 base score of 4.2.

Successful exploitation enables cross-origin data access, undermining one of the browser's core security boundaries. The vulnerability affects Chrome on Windows, macOS, and Linux platforms.

Critical Impact
An attacker with control of the renderer process can read or interact with content from origins outside the compromised context, breaking site isolation guarantees.

Affected Products

Google Chrome versions prior to 149.0.7827.155
Chrome on Microsoft Windows
Chrome on Apple macOS and Linux

Discovery Timeline

2026-06-17 - CVE-2026-12453 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-12453

Vulnerability Analysis

The vulnerability resides in Chrome's Input handling subsystem. Insufficient validation of untrusted input allows a malicious renderer to construct requests or interactions that escape the origin boundary enforced by the browser. The same-origin policy (SOP) is the foundational web security mechanism preventing one origin from reading data belonging to another, and a bypass directly exposes user data across sites.

Exploitation requires the attacker to first compromise the renderer process. This is typically achieved through chaining with a separate renderer exploit such as a memory corruption flaw in V8 or Blink. Once the renderer is under attacker control, the crafted HTML page triggers the validation gap in Input, allowing cross-origin access that should be blocked by site isolation.

The attack also requires user interaction, which constrains drive-by scenarios but does not eliminate them. Phishing pages and malicious advertisements remain viable delivery methods.

Root Cause

The root cause is improper input validation [CWE-20] within the Input component. The component fails to fully sanitize or constrain untrusted parameters originating from the renderer before acting on them. This omission allows the renderer to influence operations that should remain bound to the source origin.

Attack Vector

The attack vector is network-based. An attacker hosts a crafted HTML page and lures a victim using a vulnerable Chrome build to load it. After leveraging a prior renderer compromise, the page issues the malformed Input interaction that triggers the same-origin policy bypass. The attacker can then access information that should remain isolated to other origins.

No public proof-of-concept, exploit module, or CISA Known Exploited Vulnerabilities listing is associated with CVE-2026-12453 at this time. The EPSS probability is 0.175%.

Detection Methods for CVE-2026-12453

Indicators of Compromise

Chrome processes running versions earlier than 149.0.7827.155 after the patch availability date.
Renderer process crashes or anomalous child-process spawns preceding suspicious cross-origin network requests.
Outbound connections from chrome.exe to attacker-controlled domains immediately after visiting unfamiliar HTML content.

Detection Strategies

Inventory installed Chrome versions across managed endpoints and flag any build below 149.0.7827.155.
Monitor browser telemetry for unexpected cross-origin fetch patterns or document access events.
Correlate renderer compromise indicators (sandbox escape attempts, unusual IPC) with subsequent network egress to non-business domains.

Monitoring Recommendations

Forward Chrome installation and version data into a centralized data lake for continuous compliance reporting.
Alert on execution of Chrome binaries that have not received the vendor patch within the organization's defined SLA.
Track DNS and proxy logs for connections to domains hosting suspicious HTML payloads, particularly those referenced in phishing campaigns.

How to Mitigate CVE-2026-12453

Immediate Actions Required

Update Google Chrome to version 149.0.7827.155 or later on all Windows, macOS, and Linux endpoints.
Verify automatic update settings are enabled and that no enterprise policy is blocking Chrome auto-updates.
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 documented in the Google Chrome Update Blog. Additional technical context is available in the Chromium Issue Tracker Entry. Administrators managing Chrome through Group Policy or MDM should push the updated package promptly.

Workarounds

Restrict browsing to trusted sites via enterprise URL allow-lists until patching is complete.
Deploy strict Content Security Policy (CSP) headers on internal web applications to limit the impact of cross-origin access.
Disable or limit unnecessary Chrome extensions that increase the renderer attack surface.

bash

# Verify Chrome version on Linux endpoints
google-chrome --version

# Force update via enterprise policy on Windows (PowerShell)
Get-ItemProperty 'HKLM:\SOFTWARE\Policies\Google\Update' -Name UpdateDefault
# Ensure UpdateDefault is set to 1 (always update)