CVE-2026-89021 in MikroTik
Summary
by MITRE • 09/14/2026
MikroTik RouterOS before 7.24.2 contains a path traversal vulnerability in the container package OCI/tar image extraction that allows attackers to write files outside the container root by supplying a crafted container image with symlinks pointing to arbitrary paths. Attackers can exploit unsanitized tar member path extraction during container import via /container/add to achieve root-privileged file creation, directory creation, file deletion via overlayfs whiteout, and hardlink creation on the persistent data partition without ever starting the container. The 7.23.x long-term branch does not contain this fix; the container binaries in container-7.23.3.npk and container-7.23.4.npk are byte-identical, and there is no fixed long-term release at the time of publication.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 09/14/2026
The vulnerability identified in MikroTik RouterOS prior to version 7.24.2 represents a critical security flaw within the container management subsystem, specifically affecting the Open Container Initiative tar image extraction mechanism. This path traversal issue arises from insufficient validation of file paths contained within archived images during the import process via the /container/add API endpoint. When an attacker supplies a maliciously crafted container image containing symbolic links that point to arbitrary filesystem locations outside the designated container root directory, the system fails to sanitize these paths before extraction. Consequently, this allows for unauthorized write operations in sensitive areas of the host operating system without requiring any execution or initialization of the container itself. The flaw is rooted in the handling of tar member path data, where the software does not adequately verify that extracted files remain within their intended sandbox boundaries, thereby bypassing isolation mechanisms designed to contain container workloads.
The operational impact of this vulnerability is severe due to its ability to escalate privileges and compromise system integrity without active runtime execution. By exploiting unsanitized extraction logic, an attacker can achieve root-privileged file creation, directory manipulation, and even the deletion of critical files through overlayfs whiteout mechanisms. Furthermore, the capability to create hardlinks on the persistent data partition allows for potential persistence or further exploitation vectors that survive reboots. Since this exploit does not require starting the container, it significantly lowers the barrier for attack execution, allowing remote attackers with access to the management interface to manipulate host filesystem structures directly. This undermines the fundamental security model of containerization by breaking out of the isolated environment and interacting with the underlying router OS at a privileged level.
From an industry standards perspective, this vulnerability aligns closely with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal. The exploitation technique also relates to CWE-78: Improper Neutralization of Special Elements used in an OS Command if the extraction process invokes underlying system calls without proper sanitization. In terms of attack patterns, this falls under MITRE ATT&CK techniques involving resource hijacking and potential persistence through file system manipulation. The lack of input validation on archive contents is a classic example of trusting untrusted data sources during decompression operations, which has historically led to numerous high-severity vulnerabilities in various software ecosystems including Linux kernel utilities and web servers.
Mitigation strategies must prioritize immediate version upgrades if available within the supported release tracks. However, it is crucial to note that as of the publication details provided, the 7.23.x long-term branch does not contain this fix. The container binaries found in versions such as container-7.23.3.npk and container-23.4.npk are byte-identical, indicating that no patch was applied to these specific releases. Consequently, administrators relying on the 7.23.x long-term support line remain vulnerable until a fixed release is officially published by MikroTik. In the interim, network segmentation should be enforced to restrict access to the management interface from untrusted networks. Additionally, implementing strict firewall rules to limit API endpoint exposure and monitoring for unusual file system changes on persistent partitions can help detect potential exploitation attempts while awaiting an official patch.