CVE-2018-20751 Explained : Impact and Mitigation

A vulnerability was found in the crop_page function in PoDoFo 0.9.6, leading to a NULL pointer dereference vulnerability when processing a specially crafted PDF document.

Understanding CVE-2018-20751

What is CVE-2018-20751?

CVE-2018-20751 is a vulnerability in PoDoFo 0.9.6 that arises from a NULL pointer dereference issue in the crop_page function.

The Impact of CVE-2018-20751

The vulnerability allows attackers to exploit a NULL pointer object, potentially leading to a security breach when processing malicious PDF documents.

Technical Details of CVE-2018-20751

Vulnerability Description

The vulnerability occurs in the crop_page function of PoDoFo 0.9.6, specifically when the function call pPage->GetObject()->GetDictionary().AddKey(PdfName("MediaBox"),var) is made on a NULL pointer object pPage.

Affected Systems and Versions

Affected Version: PoDoFo 0.9.6

Exploitation Mechanism

The issue arises due to the invocation of the GetObject() function on a NULL pointer object pPage, with the variable pPage having a value of 0x0 at that stage.

Mitigation and Prevention

Immediate Steps to Take

Update PoDoFo to the latest version to patch the vulnerability.
Avoid opening PDF files from untrusted or unknown sources.

Long-Term Security Practices

Regularly update software and applications to mitigate potential vulnerabilities.
Implement network security measures to prevent malicious PDF files from being accessed.

Patching and Updates

Apply patches and updates provided by PoDoFo to address the NULL pointer dereference vulnerability.