CVE-2026-11158: macOS Chrome Sandbox Escape via AppleScript Input Validation Flaw

Technical summary

CVE-2026-11158 is an input validation flaw (CWE-20) in the Downloads component of Google Chrome on macOS versions prior to 149.0.7827.53. The vulnerability allows local privilege escalation through a sandbox escape when an attacker crafts a malicious AppleScript command that bypasses validation checks. The attack vector is local, requires no special privileges to initiate, but does require user interaction. The resulting compromise allows arbitrary code execution with Chrome's system-level permissions, potentially affecting confidentiality, integrity, and availability of the affected system.

Business impact

This vulnerability poses significant risk to organizations with macOS-based workforces using Chrome. A successful exploit could allow attackers to bypass Chrome's sandbox isolation, potentially leading to unauthorized access to system resources, sensitive data exfiltration, lateral movement to other systems on the network, or deployment of malware. Organizations that rely on Chrome's sandbox as a security boundary should treat this as a critical remediation priority. Supply chain scenarios are also concerning: an attacker could distribute a seemingly benign file or AppleScript that triggers the vulnerability when downloaded through Chrome.

Affected systems

Google Chrome on Apple macOS is affected prior to version 149.0.7827.53. This includes all macOS versions running vulnerable Chrome releases. The vulnerability is specific to the macOS platform due to its reliance on AppleScript commands; Windows and Linux Chrome versions are not affected. Organizations should inventory Chrome deployments on Mac systems and prioritize patching immediately.

Exploitability

While the Chromium project classified this as Medium severity, the CVSS 3.1 score of 8.6 (HIGH) reflects the serious sandbox-escape nature of the flaw. Exploitation requires local access to the affected system and user interaction (UI requirement in the CVSS vector), which somewhat limits widespread remote exploitation. However, the low complexity (AC:L) and no privilege requirement (PR:N) mean that any local user can potentially trigger the attack if they can convince another user to interact with a malicious file or link. The scope change (S:C) indicates that impact extends beyond the vulnerable component to the entire system. The vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities catalog, but this does not guarantee lack of active exploitation.

Remediation

Immediately update Google Chrome to version 149.0.7827.53 or later. macOS users should enable automatic Chrome updates or manually check Settings > About Google Chrome to trigger an update. IT administrators managing Chrome deployments should push this update through their device management tools (MDM/EMM) as a priority. After patching, verify that Chrome has fully restarted to ensure the new version is running. For environments that cannot immediately patch, consider restricting Chrome usage or implementing additional monitoring for suspicious local activity and AppleScript execution.

Patch guidance

Google Chrome on macOS will automatically update to version 149.0.7827.53 or later if auto-updates are enabled. To manually verify patching: open Chrome, navigate to Settings > About Google Chrome, and check the installed version number against 149.0.7827.53. The browser will automatically restart if an update is available and ready. For managed deployments, refer to Google's Chrome Enterprise release notes and MDM update policies to ensure rollout to all managed devices. Test the patch in a non-production environment before wide deployment if your organization has custom Chrome configurations or extensions.

Detection guidance

Monitor for suspicious AppleScript execution on macOS systems, particularly those involving Chrome or file download operations. Look for process execution events where AppleScript (osascript) is launched with arguments referencing Downloads directories or file manipulation commands. Endpoint Detection and Response (EDR) solutions should alert on AppleScript spawning processes with elevated privileges or system access. In Chrome's logs, watch for unusual download events combined with subsequent system calls or sandbox violation indicators. Organizations without EDR should enable System Integrity Protection (SIP) on macOS to provide an additional sandbox enforcement layer.

Why prioritize this

This vulnerability merits immediate patching due to the combination of high CVSS score (8.6), sandbox-escape capability, local attack vector, and moderate exploitability barriers (user interaction required). While not yet in active public exploitation, the technical simplicity and macOS-specific nature mean that working exploits could emerge quickly. The comprehensive impact on system confidentiality, integrity, and availability (all marked 'High' in CVSS) makes this a critical risk to Chrome users on macOS.

Risk score, explained

The CVSS 3.1 score of 8.6 reflects the severe impact of a successful sandbox escape: an attacker gains the ability to execute arbitrary code with Chrome's privileges and potentially escalate to system level. The local attack vector (AV:L) and required user interaction (UI:R) prevent this from being rated critical (9.0+), but the scope change from 'Unchanged' to 'Changed' (S:C) and high impact across all three security properties (C:H, I:H, A:H) elevate this to HIGH severity. For comparison, this score aligns with vulnerabilities that can result in complete system compromise if the preconditions are met.

Frequently asked questions