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The vulnerability CVE-2026-11307 resides in PDFium, Google’s open-source PDF rendering engine, integrated directly into Chrome. The core flaw is a Use-After-Free (CWE-416) condition in the annotation handling logic. As a PDF document is parsed and rendered, objects are allocated and deallocated in memory. Specifically, when a PDF contains specific JavaScript or Action triggers tied to an annotation, the CPDFSDK_Annot object can be freed prematurely. However, a subsequent `RenderWidget()` call still holds a stale pointer to this freed memory, attempting to access its vtable or data members. A remote attacker crafts a malicious PDF file designed to trigger this race condition. By manipulating memory layout using heap spraying techniques, the attacker can replace the freed object with attacker-controlled data. When the stale pointer is dereferenced, the browser executes arbitrary code from the crafted data. Although the vulnerability is isolated within the Chrome sandbox, successful exploitation allows an attacker to break out of the sandbox’s restrictions, leading to full remote code execution on the host system with the same privileges as the Chrome process. The Chrome security team rated the issue as “Low” based on the difficulty of reliably exploiting the use-after-free inside the sandbox. However, third-party scoring via CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H gives a base score of 8.8 (High). The bug was fixed with the stable release of Chrome version 149.0.7827.53 for Windows, Mac, and Linux. No public exploit code has been released as of the publication date, and the fix was merged in commit `43d7e733` with the message “Observe CPDFSDK_Annot across RenderWidget() call.”
DailyCVE Form
Platform: Google Chrome
Version: < 149.0.7827.53
Vulnerability: Use-After-Free
Severity: Low / CVSS 8.8
date: 2026-06-04
Prediction: Patch Date 2026-06-07
What Undercode Say
Analytics: The vulnerability scores High via CVSS 3.1 with vector AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Attack complexity is Low, no privileges required. Exploitability sub-score is 8.6, Impact sub-score 10.0.
Commands:
Check Chrome version google-chrome --version Expected version: 149.0.7827.53 or higher Search for vulnerable Chrome installations dpkg -l | grep google-chrome-stable | grep -P "149.0.7827.[0-4][0-9]" Linux Monitor PDFium activity on Linux strace -e trace=open,read,write -p $(pgrep chrome | head -1) 2>&1 | grep -i pdf
Exploit
No public exploit code has been released. A theoretical exploit would:
1. Craft a PDF with a malicious JavaScript action bound to an annotation.
2. Trigger the `RenderWidget()` call to free the CPDFSDK_Annot.
3. Use heap spraying to overwrite the freed memory with shellcode.
4. Cause a re-use of the dangling pointer, invoking the shellcode.
5. Perform a sandbox escape via a kernel exploit or by calling privileged APIs.
Protection
Update Google Chrome to version 149.0.7827.53 (Windows/Mac/Linux) or later.
Disable the Chrome PDF viewer: navigate to `chrome://settings/content/pdfDocuments` and toggle “Download PDF files instead of automatically opening them.”
Configure Chrome to open PDFs in the system’s external PDF viewer.
Apply enterprise-level group policies to force automatic updates.
Use endpoint detection rules to monitor for suspicious PDF files triggering Chrome crashes.
Impact
Successful exploitation allows an attacker to:
- Execute arbitrary code on the victim’s machine with the same privileges as Chrome.
- Read, modify, or delete local files accessible to the Chrome process.
- Install malware, ransomware, or remote access trojans.
- Use the compromised browser as a pivot point to attack internal network resources.
- Bypass Chrome’s sandbox isolation, leading to full system compromise.
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Sources:
Reported By: nvd.nist.gov
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