CVE-2026-69968 in Windows
Summary
by MITRE • 10/14/2026
Relative path traversal in Windows Libarchive allows an unauthorized attacker to perform tampering over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as a relative path traversal flaw within the Windows implementation of libarchive represents a critical security deficiency that undermines the integrity of file extraction operations performed by applications relying on this library. Libarchive is a widely used, multi-format archive and compression toolkit employed across various software ecosystems to handle compressed files such as zip, tar, gzip, and others. When processing these archives, the library must resolve relative paths contained within the archive metadata against a specified destination directory. The flaw arises from an insufficient validation mechanism when resolving these relative path components, specifically failing to adequately sanitize sequences that attempt to traverse upward in the directory hierarchy using dot-dot notation or similar constructs. This oversight allows an attacker who can influence the contents of an archive file to manipulate the final extraction location on the target system's filesystem.
From a technical perspective, this vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal or directory traversal. The core issue lies in the logic that concatenates the intended output directory with the relative paths extracted from the archive without strictly enforcing boundary constraints. An attacker can craft a malicious archive containing files with names such as ../../etc/passwd on Unix-like systems or ..\..\windows\system32\drivers\etc\hosts on Windows environments. When an application utilizing libarchive extracts this archive, the library resolves these relative paths incorrectly, causing the extracted file to be written outside the intended sandboxed directory and into arbitrary locations on the filesystem where the executing process has write permissions. This behavior violates the principle of least privilege by allowing data injection into sensitive system directories or user-specific configuration folders that were not intended for modification via archive extraction.
The operational impact of this vulnerability is significant, particularly in scenarios where applications automatically extract untrusted archives received over a network. An unauthorized attacker can exploit this flaw to perform tampering activities, such as replacing legitimate application binaries with malicious versions, injecting harmful scripts into startup directories, or corrupting critical configuration files. This capability facilitates further attacks including privilege escalation if the vulnerable process runs with elevated privileges, code execution through DLL hijacking techniques by placing a malicious dynamic link library in a directory that is searched before system paths, or denial of service by overwriting essential data files. The ability to tamper with files via network-accessible archives makes this vulnerability particularly dangerous for web servers, email gateways, and any application that processes user-uploaded compressed content without rigorous pre-processing validation.
This flaw aligns with the MITRE ATT&CK technique T1036: Masquerading, as attackers can disguise malicious payloads within legitimate-looking archive files to bypass security controls. It also relates to T1552.004: Unsecured Credentials or other file-based persistence mechanisms depending on where the attacker chooses to write their payload. The exploitation does not require authentication if the vulnerable application processes unauthenticated uploads, making it a high-risk vector for remote attackers. Mitigation strategies must focus on both immediate patching and architectural improvements. Developers should update libarchive to versions that include fixes for this path traversal issue, ensuring that all relative paths are canonicalized and validated against the target directory before extraction occurs. Additionally, applications should implement strict allow-lists for file extensions and utilize operating system-level sandboxing or chroot environments to limit the impact of any successful exploitation. Input validation at the application layer, such as rejecting archives containing path traversal sequences prior to passing them to libarchive, provides an additional defense-in-depth measure against this class of vulnerabilities.