CVE-2020-6457 Overview
CVE-2020-6457 is a use-after-free vulnerability in the speech recognizer component of Google Chrome versions prior to 81.0.4044.113. A remote attacker can exploit this flaw through a crafted HTML page to corrupt memory in the browser process. Successful exploitation can lead to a sandbox escape, allowing attacker-controlled code to break out of Chrome's renderer sandbox boundary. The issue is tracked under CWE-416 and affects Chrome on all supported desktop platforms, as well as Debian GNU/Linux 9 and 10 distributions that ship Chromium-based packages.
Critical Impact
Remote attackers can trigger memory corruption via a malicious web page and potentially escape the Chrome sandbox to execute code with elevated browser privileges.
Affected Products
- Google Chrome prior to 81.0.4044.113
- Debian GNU/Linux 9 (Stretch)
- Debian GNU/Linux 10 (Buster)
Discovery Timeline
- 2020-05-21 - CVE-2020-6457 published to the National Vulnerability Database (NVD)
- 2024-11-21 - Last updated in the NVD database
Technical Details for CVE-2020-6457
Vulnerability Analysis
The vulnerability resides in Chrome's speech recognizer subsystem, which handles Web Speech API requests originating from web content. A use-after-free condition occurs when the speech recognizer continues to reference an object after its backing memory has been freed. An attacker can manipulate the lifecycle of speech recognition objects from a crafted HTML page to control the freed allocation. Because the speech recognizer runs in a privileged browser-side process and communicates with the renderer through IPC, successful memory corruption crosses the sandbox boundary. This elevates the impact from a renderer compromise to a potential browser process compromise.
Root Cause
The root cause is improper object lifetime management within the speech recognizer (CWE-416). Code paths retain pointers to objects that have already been released, enabling dereference of dangling pointers when subsequent operations are triggered. Attackers can reclaim the freed region with attacker-controlled data to influence program flow. Additional context is available in the Chromium Bug Report #1067851.
Attack Vector
Exploitation requires a victim to load a malicious or compromised web page using a vulnerable version of Chrome. The attack vector is network-based and requires user interaction limited to visiting the page. The vulnerability scope changes because exploitation pivots from renderer to browser process, making it a sandbox escape candidate when chained with a renderer bug. No authentication is required, and the attacker does not need prior access to the target system. Refer to the Google Chrome stable channel update for desktop for vendor confirmation.
Verified exploitation code is not publicly available. The vulnerability mechanism is described in the Chromium issue tracker referenced above.
Detection Methods for CVE-2020-6457
Indicators of Compromise
- Unexpected Chrome browser process crashes accompanied by access violation or segmentation fault events in operating system crash logs.
- Outbound network connections from chrome.exe or chromium to uncategorized or newly registered domains hosting Web Speech API content.
- Creation of child processes or file writes by Chrome that deviate from normal browser behavior, indicating post-exploitation activity.
Detection Strategies
- Inventory installed Chrome and Chromium-based browser versions across endpoints and flag any build older than 81.0.4044.113.
- Correlate browser crash telemetry with web navigation history to identify pages that consistently trigger renderer or browser process termination.
- Monitor for anomalous process trees originating from the Chrome browser process, particularly spawned shells, scripting engines, or LOLBins.
Monitoring Recommendations
- Enable centralized collection of Chrome crash dumps and browser telemetry to support retrospective hunting.
- Track DNS and HTTP telemetry for visits to pages invoking the Web Speech API from unmanaged or untrusted origins.
- Alert on Chrome processes loading unexpected modules or making suspicious system calls following navigation to external content.
How to Mitigate CVE-2020-6457
Immediate Actions Required
- Update Google Chrome to version 81.0.4044.113 or later on all Windows, macOS, and Linux endpoints.
- Apply Debian security updates for Chromium packages on Debian 9 and Debian 10 systems, as outlined in Debian Security Advisory DSA-4714.
- Restart all browser instances after patching to ensure the vulnerable process is terminated and replaced.
Patch Information
Google released the fix in the Chrome stable channel update 81.0.4044.113. Details are documented in the Google Chrome stable channel update for desktop. Debian shipped patched Chromium builds via Debian Security Advisory DSA-4714. Enterprise administrators should verify Chrome auto-update policies are enabled and unobstructed by proxy or firewall configurations.
Workarounds
- Restrict access to the Web Speech API through enterprise browser policies until patching is complete.
- Deploy URL filtering to block navigation to untrusted external sites from systems running vulnerable Chrome builds.
- Where immediate patching is not feasible, isolate at-risk endpoints from sensitive network segments to limit the blast radius of a successful sandbox escape.
# Verify the installed Chrome version on Linux endpoints
google-chrome --version
# Update Chromium on Debian systems
sudo apt-get update && sudo apt-get install --only-upgrade chromium
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
