CVE-2026-13939 Overview
CVE-2026-13939 affects the WebShare component in Google Chrome on Android before version 150.0.7871.47. The vulnerability stems from insufficient validation of untrusted input, mapped to [CWE-20]. A remote attacker who has already compromised the renderer process can perform user interface (UI) spoofing through a crafted HTML page. Chromium security rated the issue Medium, while the National Vulnerability Database assigns a lower CVSS 3.1 score reflecting the required user interaction and prerequisite renderer compromise. The flaw does not enable code execution or data confidentiality loss on its own but supports secondary attacks such as phishing and permission-prompt confusion delivered via the WebShare interface.
Critical Impact
Attackers who have compromised the renderer process can spoof UI elements on Android Chrome to mislead users through the WebShare API.
Affected Products
- Google Chrome on Android prior to 150.0.7871.47
- Google Android platform builds bundling vulnerable Chrome versions
- WebView-based Android applications relying on the affected Chrome release channel
Discovery Timeline
- 2026-06-30 - CVE-2026-13939 published to the National Vulnerability Database
- 2026-07-02 - Last updated in NVD database
Technical Details for CVE-2026-13939
Vulnerability Analysis
The defect resides in the WebShare implementation in Google Chrome on Android. WebShare exposes a browser-mediated sharing dialog that the renderer can invoke via the Web Share API (navigator.share). The vulnerable code path accepts data from a renderer without adequate validation before rendering share-related UI elements. When an attacker controls a compromised renderer, the browser presents share prompts populated with untrusted content that can be styled or positioned to imitate trusted browser chrome. The result is a UI spoofing primitive rather than direct code execution, aligning with the CWE-20 improper input validation classification.
Root Cause
Chrome's WebShare handler trusts renderer-supplied strings and metadata when constructing the native Android share sheet and associated prompts. The renderer boundary is a security boundary in Chrome's multi-process model, so any content sourced from that process must be sanitized before display. In the affected versions the browser process fails to enforce those constraints on specific WebShare inputs, permitting crafted HTML in the renderer to influence overlay rendering.
Attack Vector
Exploitation requires the attacker to first compromise the renderer process, typically through a separate memory-safety bug or by controlling a site the victim visits. The attacker then serves a crafted HTML page that triggers WebShare with malicious inputs. The victim must interact with the resulting spoofed UI for the attack to succeed, which is reflected in the User Interaction Required attribute of the CVSS vector. No proof-of-concept exploit or Exploit-DB entry has been published, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the Chromium Issue Tracker #513149760 for the technical bug entry.
Detection Methods for CVE-2026-13939
Indicators of Compromise
- Android Chrome clients reporting a User-Agent version string below 150.0.7871.47
- Renderer crashes or sandbox anomalies preceding unexpected Web Share activity
- Outbound navigation to phishing destinations immediately after a share-sheet interaction
Detection Strategies
- Inventory managed Android devices and flag Chrome installations older than 150.0.7871.47 using mobile device management (MDM) telemetry
- Correlate web proxy logs with pages invoking navigator.share from newly registered or low-reputation domains
- Review browser and MDM crash reports for repeated renderer termination on the same origin, which may indicate exploit chaining
Monitoring Recommendations
- Track Chrome release advisories through the Google Chrome Stable Update channel to confirm patch adoption
- Alert on Android endpoints where automatic Chrome updates are disabled or blocked by policy
- Monitor phishing report queues for user-submitted screenshots showing share-sheet impersonation patterns
How to Mitigate CVE-2026-13939
Immediate Actions Required
- Update Google Chrome on Android to version 150.0.7871.47 or later through the Google Play Store
- Enforce automatic Chrome updates via enterprise mobility management for all Android fleet devices
- Notify users to avoid granting permissions or approving share prompts on untrusted sites until updates complete
Patch Information
Google addressed the issue in Chrome 150.0.7871.47 on the Stable channel. Details are documented in the Google Chrome Stable Update release notes, and the underlying bug is tracked at Chromium Issue Tracker #513149760.
Workarounds
- Restrict use of Chrome on Android on high-risk devices until the patched build is deployed
- Use enterprise policy to disable the Web Share API where business workflows do not require it
- Educate users to verify destination URLs after using any in-page share prompt
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
