CVE-2021-21077 in Animate
Summary
by MITRE • 03/13/2021
Adobe Animate version 21.0.3 (and earlier) is affected by a Heap-based Buffer Overflow vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve 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 • 05/04/2025
Adobe Animate version 21.0.3 and earlier contains a heap-based buffer overflow vulnerability that represents a critical security risk for users of the software. This vulnerability falls under the Common Weakness Enumeration category CWE-129, which specifically addresses insufficient size checks for buffer operations. The flaw exists within the application's handling of malformed input files, particularly those that are crafted to exploit memory management issues during file processing. Attackers can leverage this weakness by preparing a malicious file that, when opened by an unsuspecting user, triggers the buffer overflow condition in the application's memory heap.
The technical exploitation of this vulnerability requires an attacker to craft a specially designed file that exceeds the allocated buffer size during processing. When Adobe Animate attempts to parse this malformed file, the application fails to properly validate input boundaries, causing data to overflow into adjacent memory locations. This overflow can overwrite critical program memory structures and potentially inject malicious code into the execution flow. The vulnerability is classified as a remote code execution flaw because it allows attackers to execute arbitrary code on the target system with the privileges of the currently logged-in user. The attack vector requires user interaction, meaning victims must actively open the malicious file, which makes this vulnerability somewhat less automated than fully autonomous exploits but still highly dangerous in targeted campaigns.
The operational impact of this vulnerability extends beyond simple code execution, as it can lead to complete system compromise when combined with social engineering tactics. Attackers can use this vulnerability to establish persistent access, escalate privileges, or deploy additional malware payloads. The fact that exploitation requires user interaction does not diminish the risk significantly, as modern phishing campaigns and spear-phishing operations often successfully convince users to open malicious attachments. Organizations using Adobe Animate should consider this vulnerability as a high-priority threat that could be exploited in targeted attacks against creative professionals, graphic designers, and multimedia developers who regularly work with various file formats. The vulnerability also represents a potential entry point for attackers seeking to compromise broader network infrastructure through initial access via compromised creative tools.
Mitigation strategies for CVE-2021-21077 should prioritize immediate patching of Adobe Animate installations to the latest available version that addresses this specific buffer overflow issue. Organizations should implement strict file validation policies, particularly for files received from external sources or untrusted networks. Network-based protections such as email filtering and web proxy configurations can help prevent users from accessing malicious files before they reach desktop systems. Security teams should also consider implementing application whitelisting controls that restrict execution of unauthorized software and monitor for unusual file processing activities. Regular security awareness training for users can help reduce the risk of successful exploitation through social engineering. Additionally, organizations should maintain comprehensive backup strategies and incident response procedures to quickly address any potential compromise resulting from successful exploitation of this vulnerability. The ATT&CK framework categorizes this type of vulnerability exploitation under T1059 for command and script interpreter and T1203 for exploitation for client execution, highlighting the multi-stage nature of attacks that leverage such vulnerabilities.