CVE-2026-70062 in Windows
Summary
by MITRE • 10/14/2026
Double free in Windows Libarchive allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as a double free error within the Microsoft implementation of libarchive represents a critical memory management flaw that can be exploited by remote attackers to achieve arbitrary code execution. This specific defect occurs when the software incorrectly handles deallocation of memory buffers, specifically allowing two separate pointers to reference and subsequently release the same block of allocated memory. In complex parsing scenarios common in archive processing libraries like libarchive, such as those used for extracting compressed files or handling various archival formats, this logic error can be triggered by crafting malicious input data that forces the application into an execution path where a previously freed memory region is accessed again and released once more.
From a technical perspective, double free vulnerabilities are particularly dangerous because they corrupt the internal structures of the heap manager used by the operating system to track allocated memory blocks. When the first deallocation occurs, the memory block is marked as available for reuse. However, if the second deallocation proceeds without proper validation or pointer nullification, it may overwrite critical metadata associated with adjacent free chunks in the heap. This corruption can lead to unpredictable behavior ranging from application crashes and denial of service conditions to more severe consequences where an attacker gains control over program flow. By carefully crafting input that manipulates these corrupted heap structures, a skilled adversary can redirect execution pointers or inject shellcode into memory regions controlled by the vulnerable process, thereby achieving remote code execution with the privileges of the affected user account.
The operational impact of this vulnerability is severe due to its network-accessible nature and high severity rating. Since libarchive is often integrated into various Windows applications that handle file transfers, email attachments, or document processing services, an attacker does not need physical access or local authentication if the vulnerable service exposes a network interface for receiving archive files. A successful exploit could allow the unauthorized execution of code over the network, potentially leading to full system compromise, data exfiltration, lateral movement within a corporate network, and installation of persistent backdoors. The ability to execute arbitrary code remotely makes this vulnerability a prime target for automated exploitation campaigns targeting organizations that rely on services processing untrusted archive inputs.
This flaw aligns with Common Weakness Enumeration (CWE) category CWE-415, which defines Double Free as a weakness where memory is freed twice without proper re-initialization or validation of the pointer state between operations. Furthermore, in terms of tactical classification under the MITRE ATT&CK framework, this vulnerability facilitates initial access and execution phases by allowing attackers to leverage remote code execution capabilities. The exploitation typically involves sending specially crafted archive files through network services such as web servers, file sharing protocols, or email gateways that utilize libarchive for parsing.
Mitigation strategies must focus on both immediate remediation and long-term defensive engineering practices. Microsoft has released security updates addressing this specific issue in the affected versions of Windows components utilizing libarchive; organizations should prioritize applying these patches to all internet-facing systems and internal services processing archive data. For developers integrating or maintaining codebases using libarchive, it is essential to implement rigorous memory management protocols, including setting pointers to null immediately after freeing them and ensuring that no dangling references exist before subsequent deallocation attempts. Additionally, deploying network-level protections such as intrusion detection systems configured to detect anomalous file uploads containing malformed archive structures can provide an additional layer of defense against exploitation attempts while patching efforts are underway. Regular code audits focusing on memory safety in C-based libraries remain critical for preventing similar vulnerabilities in the future.