CVE-2025-21158 is an integer underflow vulnerability classified under CWE-191 affecting Adobe InDesign Desktop versions ID20.0, ID19.5.1, and earlier. The vulnerability arises from improper handling of integer values, leading to a wraparound condition that can be exploited to manipulate memory and execute arbitrary code. Specifically, when a user opens a maliciously crafted InDesign file, the integer underflow can trigger memory corruption, allowing an attacker to run code in the context of the current user. The attack vector requires local user interaction (opening a file) but no authentication or elevated privileges beforehand. The vulnerability affects confidentiality, integrity, and availability by enabling arbitrary code execution, potentially leading to data theft, system compromise, or denial of service. The CVSS 3.1 score of 7.8 reflects the high impact and relatively low complexity of exploitation, with low attack complexity and no privileges required. Although no public exploits are known yet, the widespread use of Adobe InDesign in creative industries and enterprises makes this a critical vulnerability to address promptly.

The exploitation of CVE-2025-21158 can lead to arbitrary code execution, allowing attackers to compromise affected systems fully under the current user's privileges. This can result in unauthorized access to sensitive design files, intellectual property theft, insertion of malicious content, or disruption of publishing workflows. For organizations, this could mean loss of proprietary data, reputational damage, and operational downtime. Since Adobe InDesign is widely used in media, marketing, and publishing sectors globally, the impact extends to critical creative and communication infrastructures. The requirement for user interaction (opening a malicious file) means social engineering or phishing campaigns could be used to deliver the exploit, increasing the risk of targeted attacks. The vulnerability affects confidentiality, integrity, and availability, making it a comprehensive threat to affected environments.

Organizations should implement the following specific mitigations: 1) Monitor Adobe’s security advisories closely and apply patches immediately once available to address this vulnerability. 2) Enforce strict file handling policies, including disabling automatic opening of InDesign files from untrusted sources and educating users about the risks of opening unsolicited or suspicious files. 3) Use application whitelisting and sandboxing techniques to limit the execution context of Adobe InDesign, reducing the impact of potential exploitation. 4) Employ endpoint detection and response (EDR) solutions to monitor for anomalous behavior indicative of exploitation attempts. 5) Regularly back up critical design files and maintain offline copies to ensure recovery in case of compromise. 6) Consider network segmentation to isolate systems running Adobe InDesign from sensitive environments. These targeted steps go beyond generic advice by focusing on controlling file sources, user behavior, and containment strategies.