CVE-2026-11269: Chrome Extension Sandbox Escape (v149)

Technical summary

CVE-2026-11269 stems from an inappropriate implementation in Chrome's extension handling mechanism. The vulnerability is classified under CWE-829 (Improper Restriction of Rendered UI Layers or Frames), which typically involves failures to properly isolate or validate extension content. An attacker with network adjacency can supply a specially crafted Chrome Extension that, when a user engages with it, breaks sandbox containment and executes arbitrary code. The attack vector is adjacent (AV:A), requires high complexity to exploit (AC:H), and depends on user interaction (UI:R), yet successfully bypassing the sandbox grants high confidentiality, integrity, and availability impact.

Business impact

This vulnerability threatens organizations where users browse untrusted networks or where attackers can intercept extension delivery. A successful exploit allows complete code execution within the Chrome process sandbox, potentially enabling data theft from browser memory, session hijacking, or lateral movement if the compromise is chained with other vulnerabilities. Organizations relying on Chrome's sandboxing as a security control should prioritize patching. The practical risk depends on whether users are exposed to network-adjacent attackers (common in coffee shops, airports, public WiFi, or compromised corporate networks).

Affected systems

Google Chrome browser versions below 149.0.7827.53 are vulnerable. The vulnerability affects Chrome on Windows, macOS, and Linux. The underlying issue is in Chrome's extension subsystem, which is consistent across all platforms, so users of any supported operating system running a vulnerable Chrome version require the patch.

Exploitability

Exploitation requires network adjacency to the target user and user interaction, making this a medium-complexity attack in the wild. The attacker must deliver a crafted extension to the user—either through social engineering, man-in-the-middle interception of extension updates, or hosting it on a malicious website. The high CVSS score (7.1) reflects the severe impact if successful (complete sandbox escape with code execution), not ease of exploitation. The vulnerability has not been added to CISA's Known Exploited Vulnerabilities (KEV) catalog, suggesting active exploitation in the wild has not yet been widely documented.

Remediation

Users and administrators must update Google Chrome to version 149.0.7827.53 or later. Chrome's auto-update mechanism should deploy the patch automatically, but organizations managing Chrome deployments should verify completion. No workaround exists; patching is the only fix. Users should also review installed extensions for suspicious or unnecessary ones, especially if they operate on untrusted networks.

Patch guidance

Update Chrome to version 149.0.7827.53 or later. For enterprise deployments using mobile device management or centralized Chrome policies, verify that auto-updates are enabled or push the patch directly. Check vendor advisories (Google Chrome Release Notes for version 149) for any additional guidance or related fixes. Organizations should test the patch in a staging environment if running custom extensions to ensure compatibility, though this is rarely an issue for security patches.

Detection guidance

Monitor Chrome process behavior for unexpected code execution or sandbox escape attempts. Endpoint detection and response (EDR) tools should flag instances where Chrome processes spawn child processes or access unusual system resources. Network monitoring can identify suspicious extension download patterns or man-in-the-middle attacks on extension distribution channels. Review Chrome extension audit logs in enterprise environments to detect unexpected or unauthorized extensions, particularly if they appear after the attack vector timeframe. SecurityEvent logs on Windows or system audit logs on macOS/Linux may record unusual Chrome process activity.

Why prioritize this

Although Chromium assigned this a low internal severity rating, the CVSS score of 7.1 (HIGH) reflects the real-world impact: successful exploitation grants arbitrary code execution within a browser process, a high-value target for credential theft, malware distribution, or lateral movement. Organizations where users access untrusted networks (remote workers, BYOD environments, offices with guest WiFi) face elevated risk. However, the requirement for network adjacency and user interaction limits the blast radius compared to unauthenticated remote code execution vulnerabilities. Patch within 1–2 weeks for general-risk users; within days for high-value targets or organizations with significant remote/BYOD populations.

Risk score, explained

The CVSS 3.1 score of 7.1 is driven by the following factors: Adjacent network access (AV:A) reflects the requirement for the attacker to be on the same network segment; high attack complexity (AC:H) accounts for the technical difficulty of crafting the exploit and the user interaction requirement (UI:R). The impact metrics are maximized (Confidentiality: High, Integrity: High, Availability: High) because successful sandbox escape enables unrestricted code execution within the Chrome process context. The scope is unchanged (S:U), meaning the compromise does not extend beyond the Chrome process itself. The rating reflects the severity of compromise if an exploit succeeds, weighted against the moderate difficulty of achieving that exploit in practice.

Frequently asked questions