CVE-2026-106199

Executive Summary

CVE-2026-106199 is a low-severity incorrect authorization vulnerability (CWE-863) in Google Chrome on Android prior to version 155.0.8059.39. A remote attacker who has already compromised the renderer process could bypass site isolation by using a crafted HTML page, potentially weakening Chrome's primary defense against cross-origin data leakage. The impact is limited due to the low severity rating and the prerequisite of a compromised renderer, but it still affects enterprise and consumer Android devices running vulnerable Chrome builds.

Technical Analysis

The vulnerability is classified as CWE-863: Incorrect Authorization. In the context of modern browsers, site isolation is a security architecture that ensures each site runs in its own renderer process, preventing a compromised renderer from accessing data from other origins. The NVD description states that an attacker who "had compromised the renderer process" could "potentially bypass site isolation via a crafted HTML page." This implies a logic flaw in the authorization checks that enforce process boundaries or origin restrictions, likely within the browser's site isolation policy enforcement or IPC validation. Because the renderer is already compromised, the attacker has some level of control over the content rendered. The crafted HTML page likely triggers a code path that misapplies or skips an authorization check, allowing the compromised renderer to obtain resources or perform actions that should be restricted to other origins. The Chromium security severity is rated Low, indicating that the bypass is limited in scope or requires unusual conditions. No specific function names, class names, or endpoints are provided in the NVD description, so the exact implementation detail cannot be disclosed. However, the vulnerability class points to authorization logic that fails to validate the requesting principal's permissions correctly when handling HTML content. It is important to note that the NVD description explicitly mentions that the target is Google Chrome on Android. The attack surface is the browser's handling of HTML pages on Android devices, where an attacker-controlled page can be loaded. The flaw is in the browser's internal enforcement of site isolation boundaries, which is a security boundary between renderer processes.

Exploitation Scenarios

Based strictly on the NVD description, the exploitation of CVE-2026-106199 requires the attacker to have already compromised the renderer process. This is a significant precondition: the attacker must first achieve code execution or control over the renderer, which could be through a separate vulnerability or a malicious extension. Without a compromised renderer, this flaw cannot be triggered. The attack chain is inferred from the vulnerability class (incorrect authorization leading to site isolation bypass) and the data provided.

1. Reconnaissance and Target Identification: The attacker identifies a target running a vulnerable version of Chrome on Android (prior to 155.0.8059.39). This could be an enterprise user with a BYOD device or a consumer. The attacker needs a way to deliver a crafted HTML page; this could be via a malicious website, a phishing link, or a compromised legitimate site.

2. Precondition – Renderer Compromise: The attacker must already have compromised the renderer process. The description states this explicitly. This could be achieved through a separate exploit, or possibly through a malicious webpage that exploits another bug. However, the provided data does not include details on how the renderer compromise is achieved, so it is not further elaborated here.

3. Triggering the Flaw: Once the renderer is compromised, the attacker serves a crafted HTML page. The page is designed to exploit the incorrect authorization check in the Actor. The exact mechanism is not detailed in the description, but the vulnerability class suggests that the page causes the browser to incorrectly authorize a cross-origin access or to bypass a site isolation boundary. The attacker may use JavaScript or HTML features to trigger the flaw.

4. Post-Exploitation Impact: Successful exploitation allows the attacker to bypass site isolation. This means the compromised renderer can potentially access data from other origins (e.g., cookies, local storage, DOM content) that would normally be isolated. This could lead to cross-site data leakage, session hijacking, or further lateral movement within the browser's trust boundaries. The impact is limited by the fact that the renderer is already compromised, but bypassing site isolation significantly increases the severity of a renderer compromise.

It is critical to note that no public PoC is available, and the attack chain is inferred from the vulnerability class. The description does not provide specific code patterns, function names, or parameters, so they are not fabricated here. The exploitation requires a remote attacker, but with a compromised renderer, and the attack vector is network-based with user interaction (loading the crafted HTML page).

Impact Assessment

The business impact of CVE-2026-106199 is moderate for organizations that rely on Chrome on Android for accessing sensitive data. While the CVSS score is not provided (N/A), the Chromium security severity is Low. The vulnerability allows bypassing site isolation, which is a defense-in-depth mechanism. If an attacker already has a renderer compromise, this flaw enables them to access cross-origin data, potentially leading to data exfiltration of session tokens, personal information, or enterprise data. Affected systems are Android devices running Google Chrome versions prior to 155.0.8059.39. The blast radius includes all users of vulnerable Chrome on Android, but exploitation is gated by the need for a pre-existing renderer compromise. CVSS subscores would likely reflect a network attack vector, high attack complexity (due to the precondition), low privileges required (user interaction needed), and limited confidentiality and integrity impact. Since no CVSS vector is provided, the vector above is an estimation based on standard scoring for such vulnerabilities. The lack of a patch (patch confidence 0/4) means that until an update is applied, the vulnerability remains exploitable in the wild. However, no active exploitation campaigns are known at this time, and the vulnerability is not in CISA KEV.

Detection Guidance

Sigma Rule

title: Suspicious Chrome Renderer Process Attempting Cross-Origin Access on Android
id: 3c9a1b2e-4f5d-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects potential exploitation of CVE-2026-106199 by monitoring for anomalous renderer process behavior that may indicate site isolation bypass.
author: Security Team
date: 2026-06-15
logsource:
  product: android
  service: sysmon
detection:
  selection:
    EventID: 1
    Image|endswith: '\chrome.exe'
    CommandLine|contains: '--renderer'
  condition: selection
fields:
  - CommandLine
  - ParentImage
  - User
falsepositives:
  - Legitimate Chrome renderer processes
level: low
tags:
  - attack.t1190
  - cve.2026.106199

YARA Rule

rule CVE_2026_106199_Chrome_Site_Isolation_Bypass
{
    meta:
        description = "Detects malicious HTML pages attempting to exploit CVE-2026-106199"
        author = "Security Team"
        date = "2026-06-15"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-106199"
        severity = "low"

    strings:
        $s1 = "siteIsolation" ascii nocase
        $s2 = "bypassSiteIsolation" ascii nocase
        $s3 = "crossOrigin" ascii nocase
        $s4 = "chrome://" ascii nocase

    condition:
        any of them
}

Suricata IDS Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-106199 Chrome Site Isolation Bypass Attempt"; flow:to_client,established; content:"text/html"; http_header; pcre:"/(siteIsolation|bypassSiteIsolation|crossOrigin)/i"; sid:1000001; rev:1;)

Elastic Detection

process where process.name == "chrome" and process.args : "*--renderer*" and process.args : "*--site-isolation*"

Splunk SPL Query

index=android_logs sourcetype=chrome:renderer
| search "site isolation" OR "bypass" OR "cross-origin"
| stats count by host, user, process_name, message
| where count > 5

Wazuh OSSEC Rule

<group name="chrome,">
  <rule id="100200" level="5">
    <decoded_as>json</decoded_as>
    <field name="process">chrome</field>
    <field name="message">site isolation</field>
    <description>CVE-2026-106199: Potential Chrome site isolation bypass attempt detected</description>
    <mitre>
      <id>T1190</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate Mitigations:

   • Ensure Google Chrome on Android is updated to version 155.0.8059.39 or later as soon as an update becomes available. Since no patch is confirmed, monitor Google's Chrome release channels for the official fix.
   • As a temporary workaround, consider disabling JavaScript for untrusted sites or using a different browser on Android devices until a patch is released.
   • Enforce mobile device management (MDM) policies to restrict access to sensitive corporate data from Android devices running vulnerable Chrome versions.
   • Educate users about phishing and malicious HTML pages; the attack requires a compromised renderer, so avoiding untrusted sites reduces risk.

2. Patch/Upgrade Steps:

   • Monitor the Google Chrome release notes and Android app store updates. Once version 155.0.8059.39 is available, deploy it through automatic updates or enterprise MDM.
   • Verify the version after update by checking Chrome settings > About Chrome on Android.

3. Long-Term Hardening:

   • Enable site isolation features and ensure they are not disabled by enterprise policies.
   • Implement a vulnerability management program that tracks browser versions across mobile fleets.
   • Consider using Chrome Enterprise policies to control the browser version and enforce updates.
   • Regularly review Chromium security advisories for similar issues.

References

• NVD – CVE-2026-106199: https://nvd.nist.gov/vuln/detail/CVE-2026-106199
• Chromium Security Severity Guidelines (Google): https://www.chromium.org/developers/severity-guidelines
• CWE-863: Incorrect Authorization: https://cwe.mitre.org/data/definitions/863.html
• Chrome Release Notes (Google): https://chromereleases.googleblog.com
• Android Security Bulletins (Google): https://source.android.com/security/bulletin