CVE-2025-10101 is a heap-based buffer overflow vulnerability identified in Avast Antivirus version 15.7 on macOS platforms. The vulnerability stems from improper bounds checking when processing crafted Mach-O executable files, which are native binary formats used by macOS. Specifically, the antivirus software performs an out-of-bounds write on the heap, leading to memory corruption. This flaw can be exploited locally by an attacker who can supply a malicious Mach-O file to the system, potentially allowing arbitrary code execution with the privileges of the antivirus process or causing a denial of service by crashing the antivirus protection service. The vulnerability does not require user interaction or elevated privileges but has a high attack complexity, meaning exploitation demands specific conditions or expertise. The scope of impact is significant because the antivirus software operates with elevated privileges and is critical for system security. The vulnerability is tracked under CWE-122 (Heap-based Buffer Overflow) and CWE-787 (Out-of-bounds Write). Although no public exploits are known at this time, the potential for severe impact on confidentiality, integrity, and availability is high. The vulnerability was reserved in September 2025 and published in December 2025, with no official patches yet released, emphasizing the need for vigilance and mitigation.

The impact of CVE-2025-10101 is substantial for organizations relying on Avast Antivirus on macOS. Successful exploitation can lead to local code execution, allowing attackers to bypass antivirus defenses, potentially deploying malware or gaining persistent footholds. This compromises system confidentiality and integrity, as attackers could manipulate or exfiltrate sensitive data. Additionally, denial of service attacks could disable antivirus protection, leaving systems vulnerable to other threats. Given the antivirus software’s elevated privileges, exploitation could facilitate privilege escalation or lateral movement within networks. Organizations with macOS endpoints running the affected Avast version face increased risk of targeted attacks, especially in environments where local user access is possible. The lack of known exploits currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits once details are public. The high CVSS score (8.1) reflects the critical nature of the vulnerability and its broad impact on system security.

To mitigate CVE-2025-10101, organizations should: 1) Monitor Avast’s official channels for patches and apply updates immediately upon release. 2) Restrict local user access to systems running Avast Antivirus to minimize the risk of crafted Mach-O file introduction. 3) Implement application whitelisting and file integrity monitoring to detect and prevent unauthorized or suspicious Mach-O files. 4) Employ endpoint detection and response (EDR) solutions capable of identifying anomalous behavior indicative of exploitation attempts. 5) Conduct regular security awareness training to reduce the risk of local threat vectors. 6) Consider temporarily disabling or limiting the use of Avast Antivirus on macOS in high-risk environments until patches are available, replacing it with alternative solutions if feasible. 7) Use macOS native security features such as System Integrity Protection (SIP) and sandboxing to limit the impact of potential exploits. 8) Audit and harden local user permissions to prevent unauthorized file execution or modification. These targeted measures go beyond generic advice by focusing on controlling local access and monitoring Mach-O file handling.