CVE-2026-12454: Google Chrome Privilege Escalation Flaw

CVE-2026-12454 Overview

CVE-2026-12454 is a race condition vulnerability in the Safe Browsing component of Google Chrome on macOS. The flaw affects Chrome versions prior to 149.0.7827.155. A remote attacker who has already compromised the renderer process can exploit this race to escape the Chrome sandbox using a crafted HTML page. Google rated the underlying Chromium security severity as High. The issue is tracked under [CWE-362] (Concurrent Execution using Shared Resource with Improper Synchronization).

Critical Impact
Successful exploitation enables a sandbox escape from a compromised renderer, granting the attacker code execution at the broker process privilege level on macOS hosts.

Affected Products

Google Chrome on macOS prior to 149.0.7827.155
Apple macOS (host platform for affected Chrome builds)
Chromium-based builds sharing the affected Safe Browsing code path

Discovery Timeline

2026-06-17 - CVE-2026-12454 published to the National Vulnerability Database
2026-06-18 - Last updated in NVD database
2026-06-01 - Google publishes the Chrome Stable Channel update addressing the flaw via the Chrome Stable Channel Update

Technical Details for CVE-2026-12454

Vulnerability Analysis

The vulnerability lives in Chrome's Safe Browsing subsystem on macOS. Safe Browsing performs URL and resource checks across multiple threads and processes. A race window exists between the time a check is initiated and the time its result is consumed by the trusted browser process. An attacker who already controls the renderer can manipulate timing to influence shared state during this window. The result is a sandbox escape that crosses the renderer-to-broker trust boundary. The exploitation requires user interaction and an attacker-controlled HTML page, and the attack scope changes, meaning the impact extends beyond the originally vulnerable component.

Root Cause

The root cause is improper synchronization of shared resources between threads handling Safe Browsing checks ([CWE-362]). Concurrent access to state used in security-relevant decisions allows an attacker-controlled renderer to alter the data between validation and use. This time-of-check to time-of-use pattern undermines the sandbox boundary that Chrome relies on to contain renderer compromises.

Attack Vector

Exploitation is a two-stage chain. The attacker first compromises the renderer process, typically through a separate memory corruption bug triggered by malicious web content. The attacker then loads a crafted HTML page that drives Safe Browsing operations in a controlled sequence to win the race. Because user interaction is required, the attack relies on the victim visiting an attacker-controlled or compromised site. No verified public proof-of-concept code is available for this issue. Refer to the Chromium Issue Tracker #516926968 for restricted technical detail.

// No verified proof-of-concept code is publicly available for CVE-2026-12454.
// Technical details are restricted in the Chromium issue tracker pending broad patch adoption.

Detection Methods for CVE-2026-12454

Indicators of Compromise

Unexpected child processes spawned from Google Chrome Helper or the Chrome browser process on macOS endpoints.
Chrome renderer processes performing file system or network operations outside the sandbox profile.
Crash reports or ReportCrash entries referencing Safe Browsing modules near the time of suspicious browsing activity.
Outbound connections from Chrome helper processes to previously unseen domains immediately after a user visits an unfamiliar site.

Detection Strategies

Inventory Chrome installations on macOS and flag any build below 149.0.7827.155 as vulnerable.
Monitor process lineage for renderer children that execute shell utilities, AppleScript, or osascript.
Correlate browser crash telemetry with subsequent privilege or persistence activity on the same host.
Hunt for HTML pages delivered to users that aggressively trigger Safe Browsing lookups in tight loops.

Monitoring Recommendations

Centralize Chrome version telemetry through MDM (Jamf, Kandji, Intune) and alert on outdated builds.
Forward macOS Endpoint Security and unified log events related to Chrome processes into a SIEM for retention.
Track Chrome auto-update health and surface endpoints where updates are stalled.

How to Mitigate CVE-2026-12454

Immediate Actions Required

Update Google Chrome on macOS to version 149.0.7827.155 or later across all managed endpoints.
Force a Chrome restart after update deployment so the patched binary is loaded.
Audit endpoints for evidence of sandbox escape activity prior to patch installation.
Restrict browsing to untrusted sites on unpatched hosts until the update is applied.

Patch Information

Google addressed the issue in the Chrome Stable Channel release for desktop that ships 149.0.7827.155 for macOS. Deployment details are available in the Chrome Stable Channel Update. The fix corrects synchronization in the Safe Browsing code path so that shared state cannot be altered between validation and use.

Workarounds

Disable or restrict use of Chrome on macOS until the patched version is installed where feasible.
Use macOS application allowlisting to block execution of outdated Chrome binaries.
Apply enterprise policy to disable JavaScript on untrusted sites until patching completes.

bash

# Verify the installed Chrome version on macOS
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --version

# Force Chrome to check for updates via the Keystone agent
/Library/Google/GoogleSoftwareUpdate/GoogleSoftwareUpdate.bundle/Contents/Helpers/GoogleSoftwareUpdateAgent --check