CVE-2024-7255 Overview
CVE-2024-7255 is an out-of-bounds read vulnerability in the WebTransport component of Google Chrome versions prior to 127.0.6533.88. The flaw allows a remote attacker to perform out-of-bounds memory access by serving a crafted HTML page to a target user. Google classified the Chromium security severity as High. The vulnerability is tracked under CWE-125 (Out-of-Bounds Read) and affects the WebTransport API used for low-latency bidirectional communication between browsers and servers.
Critical Impact
Remote attackers can trigger out-of-bounds memory reads by luring users to a malicious HTML page, potentially leaking sensitive process memory or enabling further exploitation of the renderer.
Affected Products
- Google Chrome versions prior to 127.0.6533.88 (Desktop)
- Chromium-based browsers incorporating the vulnerable WebTransport implementation
- Embedded applications using affected Chromium builds
Discovery Timeline
- 2024-07-30 - Google releases Stable Channel update addressing the flaw via the Chrome Releases blog
- 2024-08-01 - CVE-2024-7255 published to NVD
- 2024-10-29 - Last updated in NVD database
Technical Details for CVE-2024-7255
Vulnerability Analysis
The vulnerability resides in Chrome's WebTransport implementation, a browser API built on HTTP/3 and QUIC that enables bidirectional client-server messaging. An out-of-bounds read occurs when code reads memory beyond the bounds of an allocated buffer. In this case, the WebTransport component dereferences memory outside the intended buffer when processing attacker-controlled data delivered through a crafted HTML page.
Successful exploitation requires user interaction, specifically navigating to or interacting with attacker-controlled content. The condition triggers within the renderer process. Out-of-bounds reads in browser components can disclose memory contents such as pointers, heap layout details, or cross-origin data. Attackers commonly chain such primitives with additional flaws to escape the renderer sandbox.
Root Cause
The root cause is missing or insufficient bounds checking on a buffer accessed by the WebTransport code path. When the component processes specific WebTransport frames or session state from a crafted page, an index or pointer references memory outside the allocated region. Further technical detail is tracked in the Chromium Issue Tracker entry 352872238, which remains restricted pending broader patch adoption.
Attack Vector
Exploitation occurs over the network and requires the victim to load a crafted HTML page in a vulnerable Chrome build. The attacker hosts malicious JavaScript that opens a WebTransport session and submits data structured to drive the renderer into the vulnerable code path. No authentication is required. The vulnerability does not on its own grant code execution but provides a memory disclosure primitive that aids broader exploit chains targeting the renderer.
No verified public proof-of-concept code is available. See the Chromium Issue Tracker entry for technical details once disclosed.
Detection Methods for CVE-2024-7255
Indicators of Compromise
- Chrome browser process versions reporting below 127.0.6533.88 in endpoint inventory
- Renderer process crashes referencing WebTransport, QUIC, or HTTP/3 modules in crash dumps
- Outbound HTTP/3 or QUIC traffic on UDP port 443 to unfamiliar domains immediately after page loads
- Unexpected child processes spawned by chrome.exe following visits to untrusted sites
Detection Strategies
- Inventory installed Chrome and Chromium-based browser versions across the fleet and flag any build older than 127.0.6533.88.
- Monitor browser telemetry for renderer crashes correlated with WebTransport session establishment.
- Correlate web proxy logs with endpoint navigation events to identify users visiting suspicious sites that initiate HTTP/3 or WebTransport sessions.
Monitoring Recommendations
- Enable browser crash reporting and forward crash metadata to a centralized log platform for analysis.
- Alert on Chrome processes performing anomalous memory operations or unexpected sandbox escapes detected by endpoint protection.
- Track patch compliance through software inventory dashboards and generate weekly exception reports for non-compliant endpoints.
How to Mitigate CVE-2024-7255
Immediate Actions Required
- Update Google Chrome to version 127.0.6533.88 or later on all Windows, macOS, and Linux endpoints.
- Update Chromium-based browsers, such as Microsoft Edge, Brave, and Opera, to releases incorporating the upstream Chromium fix.
- Restart browser instances after updating to ensure the patched binaries are loaded.
- Verify automatic updates are enabled and functional through enterprise management policies.
Patch Information
Google addressed the vulnerability in Chrome Stable Channel 127.0.6533.88 for Linux and 127.0.6533.88/.89 for Windows and macOS. Refer to the Stable Channel Update for Desktop for the complete advisory and rollout details.
Workarounds
- Restrict access to untrusted websites through web filtering and DNS-based controls until patches are deployed.
- Disable or block WebTransport at the network perimeter by filtering outbound HTTP/3 traffic where operationally feasible.
- Apply enterprise policies that enforce minimum Chrome versions and prevent users from running outdated browsers.
# Enforce minimum Chrome version via enterprise policy (Windows registry)
reg add "HKLM\Software\Policies\Google\Chrome" /v "TargetVersionPrefix" /t REG_SZ /d "127.0.6533.88" /f
# Verify installed Chrome version on Linux
google-chrome --version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
