CVE-2021-39826 in Digital Editions
Summary
by MITRE • 09/28/2021
Adobe Digital Editions 4.5.11.187646 (and earlier) are affected by an arbitrary command execution vulnerability. An authenticated attacker could leverage this vulnerability to execute arbitrary commands. User interaction is required to abuse this vulnerability in that a user must open a maliciously crafted .epub file.
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Analysis
by VulDB Data Team • 05/03/2025
Adobe Digital Editions versions 4.5.11.187646 and earlier contain a critical arbitrary command execution vulnerability that poses significant security risks to end users. This vulnerability stems from insufficient input validation and sanitization within the application's handling of specially crafted epub files. The flaw allows authenticated attackers to execute arbitrary commands on the victim's system with the privileges of the logged-in user, creating a severe escalation path for potential attackers.
The technical implementation of this vulnerability involves the application's failure to properly validate file contents during the parsing process of epub documents. When a user opens a maliciously crafted epub file, the application processes the embedded content without adequate sanitization measures, allowing attacker-controlled commands to be executed within the application context. This represents a classic command injection vulnerability that falls under the CWE-77 category, specifically related to improper neutralization of special elements used in a command. The vulnerability requires user interaction through the opening of a malicious file, making it a client-side exploit that relies on social engineering tactics to succeed.
The operational impact of this vulnerability extends beyond simple command execution, as it provides attackers with full control over the victim's system. An attacker could potentially install malware, modify system files, steal sensitive data, or establish persistence mechanisms within the victim's environment. The vulnerability affects all users who have Adobe Digital Editions installed, making it particularly dangerous in enterprise environments where users may have elevated privileges. This weakness creates an attack surface that aligns with ATT&CK technique T1059.001 for command and scripting interpreter, allowing adversaries to execute commands through legitimate system interfaces.
Organizations and individual users should immediately apply the latest security patches provided by Adobe to mitigate this vulnerability. System administrators should consider implementing application whitelisting policies to restrict the execution of potentially malicious files and monitor for suspicious activity related to Adobe Digital Editions. Additionally, user education regarding the risks of opening untrusted epub files should be emphasized to reduce the success rate of social engineering attacks targeting this vulnerability. The patching process should include thorough testing to ensure compatibility with existing workflows while maintaining security posture. Regular security assessments should verify that the vulnerability has been properly addressed and that no other similar weaknesses exist within the digital publishing ecosystem.