CVE-2024-20735 in Acrobat 2020
Summary
by MITRE • 02/15/2024
Acrobat Reader versions 20.005.30539, 23.008.20470 and earlier are affected by an out-of-bounds read vulnerability that could lead to disclosure of sensitive memory. An attacker could leverage this vulnerability to bypass mitigations such as ASLR. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 06/18/2026
This vulnerability represents a critical out-of-bounds read flaw in Adobe Acrobat Reader affecting versions up to 20.005.30539 and 23.008.20470, classified under CWE-129 as improper validation of array index bounds. The technical implementation involves a memory access violation where the application fails to properly validate input data when processing maliciously crafted PDF files, leading to unauthorized memory disclosure. This flaw occurs during the parsing of PDF content where the software attempts to read memory locations beyond the allocated buffer boundaries, potentially exposing sensitive information stored in adjacent memory segments. The vulnerability directly impacts memory protection mechanisms by enabling attackers to extract information that could be used to bypass modern exploit mitigations such as address space layout randomization. The exploitation requires social engineering to convince a user to open a specifically crafted malicious file, making this a user-interaction dependent vulnerability that aligns with ATT&CK technique T1204.201 for legitimate user execution. The memory disclosure aspect provides attackers with valuable information about the target system's memory layout, potentially revealing stack canaries, heap addresses, or other security-relevant data that would otherwise remain protected. This type of vulnerability is particularly dangerous because it can be leveraged to defeat exploit mitigations, making subsequent exploitation attempts more successful. The impact extends beyond simple information disclosure as it enables more sophisticated attack vectors that could lead to arbitrary code execution or privilege escalation. Security researchers have identified that the flaw exists in the PDF parsing engine's handling of malformed array indices, where insufficient bounds checking allows memory access beyond intended limits. The vulnerability's exploitation requires a victim to perform a specific action, making it a prime candidate for targeted phishing campaigns or spear-phishing attacks. Organizations using these vulnerable versions face significant risk as attackers can use this flaw to gather system intelligence before attempting more destructive attacks. The vulnerability's classification under CWE-129 emphasizes the fundamental flaw in input validation that permits unauthorized memory access, which is a common pattern in memory safety issues within complex document processing applications. Mitigation strategies should include immediate patching of affected software versions, implementation of strict file validation policies, and user education regarding suspicious file attachments. Network-based protections such as email filtering and web application firewalls can help reduce the attack surface by blocking known malicious PDF files before they reach end users. The vulnerability demonstrates the importance of robust input validation in document processing software, particularly in applications that handle untrusted content from external sources. Organizations should also implement application whitelisting and sandboxing measures to contain potential exploitation attempts. This vulnerability type falls under the broader category of memory safety issues that affect software processing untrusted data, making it a critical concern for enterprise security teams managing document handling systems. The flaw represents a significant weakness in Adobe's security posture and highlights the need for continuous security auditing of widely used software applications that process complex file formats.