CVE-2021-21065 in Adobe
Summary
by MITRE • 02/25/2021
Adobe Bridge version 11.0 (and earlier) is affected by an out-of-bounds write vulnerability when parsing TTF files 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 • 03/05/2021
Adobe Bridge version 11.0 and earlier contains a critical out-of-bounds write vulnerability designated as CVE-2021-21065 that stems from insufficient input validation during the parsing of TrueType Font files. This vulnerability resides in the font processing library and manifests when the application attempts to handle malformed TTF structures that exceed allocated memory boundaries. The flaw falls under the Common Weakness Enumeration category CWE-787, which specifically addresses out-of-bounds write conditions that can lead to memory corruption and arbitrary code execution. The vulnerability is particularly concerning because it requires only user interaction to exploit, making it highly susceptible to social engineering attacks where victims might unknowingly open malicious font files.
The technical exploitation of this vulnerability occurs when Adobe Bridge processes a specially crafted TTF file that contains malformed data structures. During the parsing operation, the application fails to properly validate the size and structure of font tables, leading to memory corruption when the parser attempts to write data beyond the allocated buffer boundaries. This memory corruption can be manipulated to overwrite critical program memory locations, potentially allowing an attacker to execute arbitrary code with the privileges of the current user. The attack vector is particularly dangerous because it leverages the normal operation of the application, as users frequently interact with font files during creative workflows. The vulnerability does not require elevated privileges to exploit, making it accessible to attackers who can convince victims to open malicious files through various means such as email attachments, compromised websites, or infected USB drives.
The operational impact of CVE-2021-21065 extends beyond simple code execution, as it represents a significant threat to creative professionals who rely on Adobe Bridge for their workflow. Attackers could potentially use this vulnerability to install malware, steal sensitive data, or establish persistent access to compromised systems. The vulnerability affects the entire Adobe Bridge ecosystem, including users who may not be technically savvy and could be easily tricked into opening malicious files. This makes the exploit particularly dangerous in enterprise environments where creative teams frequently exchange files and may inadvertently expose themselves to attacks. The vulnerability also demonstrates the broader security implications of font processing libraries, as similar issues have been identified in other applications that parse font files, indicating a pattern of insufficient input validation in graphics and typography components.
Organizations should prioritize immediate remediation by updating to Adobe Bridge version 11.1 or later, which contains the necessary patches to address this vulnerability. System administrators should implement strict file validation policies and consider deploying sandboxing solutions for font processing operations. The mitigation strategy should include user education about the dangers of opening unknown font files and implementing network-based protections such as web application firewalls that can detect and block malicious font file content. Security teams should monitor for exploitation attempts and consider implementing behavioral monitoring to detect anomalous font processing activities. This vulnerability also highlights the importance of following secure coding practices and conducting regular security assessments of third-party libraries used in creative applications. The incident underscores the need for comprehensive security testing of graphics processing components and demonstrates how seemingly benign file formats can become attack vectors when proper input validation is absent.