CVE-2026-11242: Chrome Plugin Input Validation Flaw Enables Cross-Origin Data Leakage

Technical summary

CVE-2026-11242 involves insufficient input validation in Chrome's plugin handling code. The vulnerability exists in the renderer process and allows cross-origin data leakage when a crafted HTML page is processed. The attack vector is network-based with no special privileges required and no user interaction needed once the renderer is compromised. The root cause is CWE-20 (Improper Input Validation), which permits an attacker to bypass browser security boundaries and access data from origins other than the current page. Chromium's internal severity assessment was Low, though the CVSS 3.1 score of 7.5 (High) reflects the confidentiality impact of successful exploitation.

Business impact

If exploited, this vulnerability could allow attackers to exfiltrate sensitive user data such as authentication tokens, personal information, or confidential business data accessed through the browser. The risk is heightened in environments where users visit untrusted websites or where an initial compromise of the renderer process has already occurred. Organizations relying on Chrome for accessing sensitive cloud services or internal web applications should prioritize patching to prevent data breach scenarios. The confidentiality impact is high (full disclosure possible), though integrity and availability are not affected.

Affected systems

Google Chrome prior to version 149.0.7827.53 is directly affected. Because Chrome is distributed across Windows, macOS, and Linux systems listed in the vendor data, all three operating systems are in scope. Users on any supported platform running an unpatched version are vulnerable if the renderer process is compromised. Enterprise deployments using Chrome across multiple OSes should treat this as a universal patching requirement.

Exploitability

Exploitation requires an attacker to first compromise the Chrome renderer process, making this a post-compromise vulnerability. Once the renderer is compromised, the attack can be executed remotely via a crafted HTML page with no additional user interaction. The network attack vector and low complexity make it relatively straightforward to exploit in practical attack chains. The vulnerability does not appear in the CISA Known Exploited Vulnerabilities (KEV) catalog, indicating no current evidence of active, widespread exploitation, though the technical barriers to weaponization are modest.

Remediation

Update Google Chrome to version 149.0.7827.53 or later. Users should enable automatic updates in Chrome settings to receive patches without manual intervention. For enterprise environments, use Chrome's managed update policies to enforce patching across deployed instances. Verify the update by navigating to Chrome menu > About Google Chrome, which will show the current version and trigger any pending updates. No workarounds are available for unpatched versions; patching is the only effective mitigation.

Patch guidance

Patch availability: Chrome version 149.0.7827.53 and later. For individual users, Chrome's automatic update mechanism will deploy the patch; check Settings > About Google Chrome to trigger or verify the update. Enterprise administrators should deploy via group policy (Windows), Jamf or similar MDM (macOS), or system package managers (Linux). Test the patch in non-production Chrome instances first if possible, though the risk of regression is low for this targeted fix. Verify patching across all user devices before considering the vulnerability fully remediated.

Detection guidance

Monitor for unusual plugin behavior or unexpected data access patterns in browser logs if forensic investigation is needed. Network monitoring for exfiltration attempts from compromised systems could help detect active exploitation. Chrome logs and renderer process diagnostics may show signs of plugin misuse. Note that successful exploitation occurs within the browser and may not produce visible alerts without enhanced logging. Focus detection efforts on identifying renderer process compromises first, as that is the prerequisite for this vulnerability to be exploitable. Security Event Log monitoring on Windows systems for suspicious process creation or memory access can provide indirect signals.

Why prioritize this

This vulnerability should be prioritized due to the high CVSS score (7.5), the potential for broad data exfiltration, and the universal presence of Chrome across virtually all organizations. Although it requires a prior renderer compromise, it poses a significant secondary risk in multi-stage attack chains. The lack of KEV status should not lower urgency, as the vulnerability is recent and actively being disclosed. Organizations should treat patching as time-sensitive given the high confidentiality impact and the maturity of exploitation techniques once the renderer is compromised.

Risk score, explained

CVSS 3.1 score of 7.5 (High) is driven by a high confidentiality impact (C:H), zero integrity impact (I:N), and zero availability impact (A:N). The attack vector is network (AV:N), attack complexity is low (AC:L), no privileges are required (PR:N), and no user interaction is needed (UI:N). The scope is unchanged (S:U), meaning the attack is confined to the vulnerable component. While Chromium's internal assessment was Low, the CVSS score appropriately reflects the potential for broad, sensitive data disclosure. The gap between the two severity ratings is notable and suggests the CVSS scoring emphasizes the confidentiality breach potential over other factors.

Frequently asked questions