CVE-2024-7973: Google Chrome Buffer Overflow Vulnerability

CVE-2024-7973 Overview

CVE-2024-7973 is a heap buffer overflow vulnerability in PDFium, the PDF rendering engine embedded in Google Chrome. The flaw affects Chrome versions prior to 128.0.6613.84. A remote attacker can trigger an out-of-bounds memory read by convincing a user to open a crafted PDF file. The issue is tracked under [CWE-122] Heap-based Buffer Overflow and [CWE-787] Out-of-bounds Write. Google classified the Chromium security severity as Medium, while NVD assigned a CVSS 3.1 base score of 8.8.

Critical Impact
A remote attacker can trigger memory corruption in the browser process by delivering a malicious PDF, potentially leading to information disclosure or code execution in the renderer sandbox.

Affected Products

Google Chrome versions prior to 128.0.6613.84
Chromium-based browsers embedding vulnerable PDFium builds
Applications integrating unpatched PDFium as a library

Discovery Timeline

2024-08-21 - Google releases Chrome 128.0.6613.84 addressing the flaw
2024-08-21 - CVE-2024-7973 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-7973

Vulnerability Analysis

The vulnerability resides in PDFium, the open-source PDF library that Chrome uses to parse and render PDF documents. Attackers exploit the flaw by delivering a crafted PDF that manipulates PDFium into reading memory outside the bounds of an allocated heap buffer. Exploitation requires user interaction, typically opening a malicious PDF hosted on a webpage or delivered by email.

Successful exploitation can expose adjacent heap memory contents. Attackers often chain such reads with additional flaws to defeat address space layout randomization (ASLR) and pivot toward remote code execution inside the renderer process. The renderer sandbox limits direct system impact, but combined with a sandbox escape, the vulnerability can lead to full compromise of the host.

The EPSS model rates this issue with a probability of 0.732% and a percentile of 49.7, indicating moderate near-term exploitation likelihood among tracked CVEs.

Root Cause

The root cause is improper bounds validation in PDFium heap buffer handling. The parser dereferences pointers or indexes into a heap allocation without verifying that the calculated offset remains within the buffer size. Malformed PDF structures manipulate the size or offset fields, causing PDFium to read past the buffer boundary.

Attack Vector

The attack vector is network-based with low complexity and requires user interaction. An attacker hosts or delivers a specially crafted PDF file. When the victim opens the file in Chrome or loads a page that renders the PDF inline, PDFium processes the malicious content and triggers the heap out-of-bounds read.

No verified public proof-of-concept code is available. See the Chromium Issue Tracker Item and the Google Chrome Stable Update for vendor-provided technical context.

Detection Methods for CVE-2024-7973

Indicators of Compromise

Chrome renderer process crashes with heap corruption signatures while rendering PDF content
Unexpected PDF downloads from untrusted domains followed by browser instability
Endpoint logs showing chrome.exe child processes terminating abnormally after PDF navigation

Detection Strategies

Inventory installed Chrome versions and flag any build earlier than 128.0.6613.84
Monitor web proxy and email gateway telemetry for PDF attachments originating from low-reputation sources
Correlate browser crash reports with PDF file opens using endpoint telemetry

Monitoring Recommendations

Enable browser crash reporting and forward events to the SIEM for triage
Track PDF file downloads and executions across managed endpoints
Alert on renderer process anomalies such as repeated crashes tied to pdfium.dll or libpdfium

How to Mitigate CVE-2024-7973

Immediate Actions Required

Update Google Chrome to version 128.0.6613.84 or later on all endpoints
Restart Chrome after patching to ensure the updated PDFium module is loaded
Audit Chromium-derived browsers (Edge, Brave, Opera, Vivaldi) for corresponding patched builds

Patch Information

Google addressed the vulnerability in the Chrome Stable channel release 128.0.6613.84 for Windows, macOS, and Linux, announced in the Google Chrome Stable Update. Enterprises using managed Chrome deployments should push the update through Group Policy, Chrome Browser Cloud Management, or their software distribution platform.

Workarounds

Disable the internal PDF viewer via the AlwaysOpenPdfExternally enterprise policy until patching is complete
Block inbound PDF attachments from untrusted senders at the email gateway
Restrict PDF downloads from uncategorized or newly registered domains through web proxy policies

bash

# Enforce external PDF handling via Chrome enterprise policy (Windows registry)
reg add "HKLM\Software\Policies\Google\Chrome" /v AlwaysOpenPdfExternally /t REG_DWORD /d 1 /f

# Verify installed Chrome version on Linux endpoints
google-chrome --version