CVE-2024-20729 in Acrobat 2020
Summary
by MITRE • 02/15/2024
Acrobat Reader versions 20.005.30539, 23.008.20470 and earlier are affected by a Use After Free vulnerability that could result in arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
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Analysis
by VulDB Data Team • 07/06/2026
This vulnerability represents a critical use after free condition in Adobe Acrobat Reader affecting multiple version ranges including 20.005.30539 and 23.008.20470 along with earlier releases. The flaw occurs when the application processes maliciously crafted PDF files that trigger improper memory management during object deallocation, creating a scenario where freed memory locations may be accessed or reused by subsequent operations. This type of vulnerability falls under the common weakness enumeration CWE-416 which specifically addresses use after free conditions in software applications. The security implications are severe as attackers can manipulate the application's memory state to execute arbitrary code with the privileges of the currently logged-in user, potentially leading to complete system compromise.
The exploitation mechanism requires social engineering through user interaction since victims must voluntarily open the malicious file for the vulnerability to be triggered. This user interaction requirement makes the attack vector more constrained but also more targeted, as it relies on users being tricked into opening suspicious documents. The attack typically involves crafting a specially formatted PDF document that, when processed by the vulnerable Acrobat Reader version, causes the application to free memory associated with certain objects and then subsequently access that same memory location during normal processing operations. This creates an opportunity for attackers to overwrite memory contents with malicious payloads or redirect execution flow through controlled data manipulation.
The operational impact of this vulnerability extends beyond simple code execution as it represents a privilege escalation vector that can be leveraged for persistent access to affected systems. When successfully exploited, the malicious code runs within the context of the Acrobat Reader process which typically has the same user privileges as the victim, potentially allowing attackers to access sensitive documents, credentials, or system resources. This vulnerability is particularly concerning in enterprise environments where Acrobat Reader is widely deployed for document viewing and business-critical workflows. Organizations using these vulnerable versions face significant risk from targeted attacks, especially those involving spear-phishing campaigns or supply chain compromises that could deliver malicious PDF files to unsuspecting users.
Organizations should prioritize immediate remediation by updating to the latest available versions of Adobe Acrobat Reader where this vulnerability has been addressed through proper memory management fixes and heap allocation protections. System administrators should implement network-based controls such as PDF file filtering at perimeter defenses, disable unnecessary PDF processing features, and maintain strict monitoring for suspicious document handling activities. The mitigation strategy should include user education regarding dangerous file attachments, implementation of email security solutions capable of identifying malicious PDF content, and regular patch management procedures to ensure all endpoints remain protected against known vulnerabilities. Additionally, organizations may consider deploying application whitelisting controls that restrict Acrobat Reader execution to trusted environments only, while also monitoring for unusual process behavior or memory access patterns that could indicate exploitation attempts.