CVE-2021-21046 in Acrobat Reader
Summary
by MITRE • 02/12/2021
Acrobat Reader DC versions versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by an memory corruption vulnerability. An unauthenticated attacker could leverage this vulnerability to cause an application denial-of-service. 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 • 02/28/2021
This vulnerability exists in Adobe Acrobat Reader DC versions prior to specific patches, representing a memory corruption flaw that can lead to denial-of-service conditions. The vulnerability affects multiple version lines including 2020.013.20074 and earlier, 2020.001.30018 and earlier, and 2017.011.30188 and earlier, indicating a widespread issue across different release branches of the software. The memory corruption occurs during the processing of maliciously crafted files, where improper memory handling leads to application instability and potential crashes. This type of vulnerability falls under the category of memory safety issues and can be classified as a CWE-125 vulnerability, which represents out-of-bounds read conditions that can result in memory corruption. The vulnerability is particularly concerning because it requires only user interaction to exploit, making it a significant threat vector in targeted attacks or social engineering campaigns.
The technical execution of this vulnerability requires an attacker to craft a malicious file that, when opened by an affected Acrobat Reader DC version, triggers the memory corruption. This typically involves manipulating file structures or content in a way that causes the application to improperly handle memory allocation or access patterns. The attack scenario involves a victim opening a specially crafted document, which could be delivered through email attachments, malicious websites, or other file-sharing mechanisms. The memory corruption results in application instability that manifests as crashes, hangs, or other denial-of-service conditions that prevent legitimate document processing. From an attack framework perspective, this vulnerability aligns with techniques described in the ATT&CK framework under initial access and execution phases where adversaries leverage software vulnerabilities to compromise target systems.
The operational impact of this vulnerability extends beyond simple denial-of-service conditions as it can disrupt legitimate business processes that depend on document processing capabilities. Organizations relying on Acrobat Reader for document review, contract signing, or other critical workflows may experience service interruptions when malicious documents are encountered. The vulnerability's requirement for user interaction makes it particularly dangerous in environments where users frequently open documents from external sources or untrusted senders. Security teams must consider the broader implications of this vulnerability, including potential for escalation if the memory corruption leads to more severe exploitation vectors. The vulnerability also represents a risk to user productivity and organizational efficiency, as users may encounter unexpected application failures when processing legitimate documents. Mitigation strategies should focus on immediate patch deployment, user education about suspicious file attachments, and implementation of email filtering and document scanning mechanisms to prevent exploitation. The vulnerability demonstrates the importance of maintaining up-to-date security patches and the risks associated with running outdated software versions in enterprise environments.