CVE-2026-106209

Executive Summary

CVE-2026-106209 is a UI misrepresentation (spoofing) vulnerability in Google Chrome on iOS versions prior to 155.0.8059.39. A remote attacker can exploit this flaw by leveraging social engineering to spoof the address bar via a crafted HTML page. While the CVSS score is Medium (5.4), the vulnerability undermines user trust in the browser's security indicators, potentially facilitating phishing or credential theft. There is currently no public proof-of-concept, exploit code, or evidence of in-the-wild exploitation.

Technical Analysis

The vulnerability is classified as CWE-451: User Interface (UI) Misrepresentation of Critical Information. In the context of Google Chrome on iOS, this means that a crafted HTML page can cause the browser to display incorrect or misleading information in its address bar. The address bar is a critical security indicator that users rely upon to verify the authenticity of the website they are visiting. By spoofing the address bar, an attacker can make a malicious site appear as a trusted domain (e.g., a bank or email provider), thereby tricking the user into entering sensitive information or downloading malware.

The attack surface is the rendering engine's handling of specific HTML content that affects the UI layer. The vulnerability requires user interaction (UI:R) and is network-accessible (AV:N) with low attack complexity (AC:L) and no privileges required (PR:N). The exact code-level flaw—such as improper sanitization of URL display, failure to update the address bar during navigation, or a race condition in the UI update—is not detailed in the NVD description. The description explicitly mentions "social engineering" and "spoof address bar," indicating that the flaw is exploitable only through user deception, not through direct code execution.

The Chromium security severity is rated as Medium, aligning with the CVSS 5.4. The integrity impact is None (I:N), confidentiality impact is Low (C:L), and availability impact is Low (A:L). This suggests that while the attacker cannot directly modify data or cause a denial of service, they can potentially leak limited information (e.g., credentials entered by the user) or cause minor disruption (e.g., browser tab confusion). The scope is unchanged (S:U), meaning the vulnerability does not affect resources beyond the browser's security context.

It is important to note that this vulnerability is specific to Chrome on iOS. The underlying rendering engine on iOS is WebKit (due to Apple's App Store policies), but Chrome uses its own UI layer. The flaw likely resides in how Chrome's UI handles the address bar in response to crafted HTML, possibly through JavaScript or CSS that manipulates the visual presentation. Without a public advisory or patch details, the precise mechanism remains undisclosed. No public PoC or exploit code is available, and no Nuclei template exists.

Exploitation Scenarios

No public PoC is available; the attack chain is inferred from the vulnerability class (CWE-451: UI Misrepresentation). The following is a generic exploitation scenario based on the NVD description.

1. Reconnaissance/Target Identification: The attacker identifies a target audience that uses Google Chrome on iOS. This could be achieved through phishing campaigns, malicious advertisements, or social media posts that direct users to a crafted webpage.

2. Triggering the Flaw: The attacker hosts a crafted HTML page on a malicious domain. When a victim visits the page using a vulnerable version of Chrome on iOS, the page exploits the UI misrepresentation flaw to spoof the address bar. This could involve manipulating the browser's URL display to show a legitimate domain (e.g., "https://www.example-bank.com") while the actual content is served from the attacker's domain.

3. Payload/Execution Method: The "payload" is purely the spoofed UI. No code execution is required. The attacker may combine this with a phishing page that mimics a login form, prompting the user to enter credentials. The crafted HTML page leverages social engineering to convince the user that they are on a trusted site, thereby lowering their guard.

4. Post-Exploitation Impact: Successful exploitation allows the attacker to harvest credentials, personal information, or financial data entered by the victim. The low confidentiality impact (C:L) reflects the potential for limited information disclosure. The low availability impact (A:L) could result from the user being unable to navigate away or the browser becoming unresponsive due to the spoofing trick. The attacker does not gain direct access to the device or browser internals; the impact is confined to the user's interaction with the spoofed UI.

Given the lack of specific technical details, it is not possible to describe exact HTML tags, JavaScript APIs, or URL parameters involved. The attack relies on the browser's failure to correctly represent the address bar, a class of vulnerabilities that has historically been exploited in phishing campaigns.

Impact Assessment

The business impact of CVE-2026-106209 is primarily reputational and financial for organizations whose users are targeted. If employees or customers are tricked into entering credentials on a spoofed site, the organization may suffer data breaches, account takeovers, and financial fraud. The blast radius is limited to users of Google Chrome on iOS who interact with the crafted page. The affected systems are mobile devices running iOS with a vulnerable Chrome version.

The CVSS vector (AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L) indicates that exploitation is network-based, requires no privileges, and depends on user interaction. The low confidentiality and availability impacts suggest that the attacker cannot directly exfiltrate large amounts of data or cause significant disruption. However, the integrity of the UI is compromised, which can have cascading effects on user trust and security. Because the vulnerability is unpatched (patch confidence 0/4), all users of Chrome on iOS below version 155.0.8059.39 are at risk. There is no evidence of active exploitation, and CISA KEV does not list this CVE.

Detection Guidance

Sigma Rule

title: Potential Chrome iOS Address Bar Spoofing Attempt
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects crafted HTML pages attempting to spoof the address bar in Chrome on iOS (CVE-2026-106209)
author: Threat Intelligence Team
date: 2026-05-20
logsource:
    category: webserver
    product: apache
detection:
    selection:
        http.method: 'GET'
        http.useragent|contains: 'CriOS'
        http.response.body|contains|all:
            - '<script'
            - 'location'
            - 'address'
    condition: selection
falsepositives:
    - Legitimate web applications that manipulate the URL display
level: medium
tags:
    - attack.t1204
    - cve.2026.106209

YARA Rule

rule CVE_2026_106209_Chrome_iOS_AddressBar_Spoof
{
    meta:
        description = "Detects HTML pages attempting to spoof Chrome iOS address bar"
        author = "Threat Intelligence Team"
        date = "2026-05-20"
        reference = "CVE-2026-106209"
        severity = "medium"

    strings:
        $s1 = "address bar" nocase
        $s2 = "spoof" nocase
        $s3 = "CriOS" nocase
        $s4 = "window.location" nocase

    condition:
        (uint16(0) == 0x3C21 or uint16(0) == 0x6874) and
        (2 of ($s*))
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-106209 Chrome iOS Address Bar Spoofing Attempt"; flow:to_client,established; content:"CriOS"; http_user_agent; content:"<script"; http_response_body; content:"location"; http_response_body; classtype:attempted-recon; sid:1000001; rev:1;)

Elastic Detection

network where process.name == "Google Chrome" and network.protocol == "http" and
  http.request.user_agent : "*CriOS*" and http.response.body : "*address bar*" and
  http.response.body : "*location*" and http.response.body : "*spoof*"

Splunk SPL Query

index=web sourcetype=access_combined
| search useragent="*CriOS*" AND (uri="*address*" OR uri="*spoof*" OR uri="*location*")
| stats count by src_ip, uri, useragent
| where count > 0

Wazuh OSSEC Rule

<group name="web,chrome,cve-2026-106209">
  <rule id="100210" level="5">
    <decoded_as>web-accesslog</decoded_as>
    <field name="id">CriOS</field>
    <regex>.*address bar.*</regex>
    <description>CVE-2026-106209: Potential Chrome iOS address bar spoofing attempt detected.</description>
    <mitre>
      <id>T1204</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

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

1. Immediate Mitigations:

   • Advise users to update Google Chrome on iOS to version 155.0.8059.39 or later as soon as it becomes available. Since no patch is confirmed, monitor official Google Chrome release channels for security updates.
   • Implement user awareness training to recognize phishing attempts and verify URLs through other means (e.g., tapping the address bar to see the full URL, using bookmarks).
   • Consider restricting the use of Chrome on iOS for high-risk activities until a patch is released, or enforce the use of alternative browsers with stronger anti-spoofing measures.

2. Patch/Upgrade Steps:

   • Once a patched version is released, instruct users to update via the Apple App Store. Ensure automatic updates are enabled.
   • Verify the installed version by navigating to chrome://version (if accessible) or through the App Store.

3. Long-term Hardening:

   • Deploy mobile device management (MDM) policies to enforce minimum browser versions and block outdated versions.
   • Implement network-level detection and filtering for known phishing domains and crafted HTML patterns.
   • Encourage the use of security keys or biometric authentication to mitigate credential theft even if spoofing occurs.

References

• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-106209
• Google Chrome Release Notes: https://chromereleases.googleblog.com/
• CWE-451: https://cwe.mitre.org/data/definitions/451.html
• MITRE ATT&CK T1204: https://attack.mitre.org/techniques/T1204/
• Chromium Security Severity Guidelines: https://www.chromium.org/developers/severity-guidelines/