CVE-2025-1918: Google Chrome Buffer Overflow Vulnerability

CVE-2025-1918 Overview

CVE-2025-1918 is an Out-of-Bounds Read vulnerability in PDFium, the PDF rendering engine used by Google Chrome. This memory safety issue exists in Chrome versions prior to 134.0.6998.35 and can be triggered when the browser processes a specially crafted PDF file. A remote attacker could exploit this vulnerability to perform out-of-bounds memory access, potentially leading to information disclosure or arbitrary code execution.

Critical Impact

Remote attackers can exploit this vulnerability by delivering a malicious PDF file to victims, potentially gaining unauthorized access to sensitive memory contents or achieving code execution within the Chrome browser context.

Affected Products

• Google Chrome versions prior to 134.0.6998.35
• All platforms running vulnerable Chrome versions (Windows, macOS, Linux)
• Chromium-based browsers using the affected PDFium component

Discovery Timeline

• 2025-03-05 - CVE-2025-1918 published to NVD
• 2025-04-01 - Last updated in NVD database

Technical Details for CVE-2025-1918

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-bounds Read), a memory safety issue that occurs when software reads data past the end or before the beginning of an intended buffer. In the context of PDFium, this vulnerability is triggered during the parsing or rendering of malformed PDF content.

Out-of-bounds read vulnerabilities in PDF rendering engines are particularly dangerous because they operate on untrusted content from the internet. When Chrome's PDFium component processes a specially crafted PDF file, the parser may incorrectly calculate buffer boundaries, allowing memory access beyond allocated regions. This can result in disclosure of sensitive information from adjacent memory regions or potentially be chained with other vulnerabilities to achieve code execution.

The network-based attack vector means exploitation requires user interaction—specifically, a victim must open or preview a malicious PDF file delivered via email, a compromised website, or other delivery mechanisms.

Root Cause

The root cause of this vulnerability lies in improper bounds checking within PDFium's PDF processing logic. When parsing specific PDF structures, the code fails to properly validate that read operations remain within the allocated buffer boundaries. This allows an attacker to craft a PDF file that triggers read operations beyond the intended memory region.

Attack Vector

The attack is network-based and requires user interaction. An attacker can exploit this vulnerability through several delivery mechanisms:

1. Malicious Website: Hosting a crafted PDF that auto-downloads or renders in-browser when a victim visits the page
2. Email Attachment: Sending the malicious PDF as an attachment that triggers when opened in Chrome's built-in PDF viewer
3. Drive-by Download: Embedding the PDF in compromised websites or malicious advertisements

When a victim opens the malicious PDF in Google Chrome, the PDFium component attempts to parse the crafted content. The specially constructed PDF structures cause the parser to read memory outside the intended buffer boundaries, potentially exposing sensitive data or causing further exploitation.

Detection Methods for CVE-2025-1918

Indicators of Compromise

• Unexpected Chrome browser crashes or instability when viewing PDF files
• Anomalous network traffic originating from Chrome processes after PDF viewing
• Detection of PDF files with malformed or unusual internal structures
• Memory access violations logged in system crash dumps related to Chrome or PDFium

Detection Strategies

• Monitor endpoint telemetry for Chrome crashes with memory access violations during PDF rendering
• Implement network-based detection for PDF files containing suspicious object structures
• Deploy behavioral analysis to detect anomalous Chrome process activity following PDF access
• Utilize SentinelOne's Singularity XDR to correlate PDF access events with subsequent suspicious process behaviors

Monitoring Recommendations

• Enable enhanced logging for browser activities and PDF file access events
• Configure SentinelOne agents to alert on Chrome crash events with memory corruption indicators
• Monitor for unusual child processes spawned by Chrome after PDF interactions
• Implement file scanning for inbound PDF attachments using signature and heuristic detection

How to Mitigate CVE-2025-1918

Immediate Actions Required

• Update Google Chrome to version 134.0.6998.35 or later immediately
• Enable automatic Chrome updates to ensure timely patching of future vulnerabilities
• Consider disabling Chrome's built-in PDF viewer and using an alternative, sandboxed PDF reader
• Implement email gateway scanning to detect and block malicious PDF attachments
• Educate users about the risks of opening PDF files from untrusted sources

Patch Information

Google has addressed this vulnerability in Chrome version 134.0.6998.35. The fix was announced in the Google Chrome Desktop Update on March 2025. Technical details about the issue can be found in Chromium Issue Tracking #388557904.

Organizations should prioritize deploying this update across all managed Chrome installations. Chrome typically auto-updates, but enterprise environments with managed browsers should verify update deployment through their management consoles.

Workarounds

• Disable Chrome's built-in PDF viewer by navigating to chrome://settings/content/pdfDocuments and selecting "Download PDFs"
• Use alternative PDF viewers with strong sandboxing capabilities for sensitive documents
• Implement network-level filtering to scan and sanitize PDF files before they reach end users
• Apply application control policies to restrict Chrome's ability to access sensitive memory regions
• Consider using Chrome's Site Isolation feature and ensure it is enabled for additional process-level protection

# Verify Chrome version is patched
google-chrome --version
# Expected output: Google Chrome 134.0.6998.35 or higher

# Force Chrome update check (user-initiated)
# Navigate to: chrome://settings/help
# Chrome will automatically check for and apply updates

# Enterprise deployment verification (Windows)
# Check registry for Chrome version:
reg query "HKEY_LOCAL_MACHINE\SOFTWARE\Google\Chrome\BLBeacon" /v version