zrok 'copy' Path Traversal Vulnerability (CVE-2026-45576)

A path traversal vulnerability has been identified in the zrok copy command, affecting versions prior to 2.0.3 and versions 0.4.23 through 1.1.11. The vulnerability, tracked as CVE-2026-45576, allows a malicious actor controlling a WebDAV or zrok drive to write files outside the intended destination root on a victim’s system. This is achieved by manipulating the DAV href response to include path traversal sequences like /../ which, when processed by the FilesystemTarget.WriteStream function, allows writing arbitrary files within the sharing user’s credentials. This poses a significant risk of sensitive information being overwritten.

Attack Chain

1. Bob sets up a malicious WebDAV server or a zrok drive.
2. Bob crafts a DAV href response containing path traversal sequences, such as /../outside.txt.
3. Alice executes the zrok2 copy command, specifying Bob’s malicious WebDAV server or zrok drive as the source and a local directory as the destination.
4. The zrok2 copy process retrieves the directory listing from Bob’s server, including the crafted href value.
5. The zrok2 copy process stores the malicious path in the source inventory.
6. The FilesystemTarget.WriteStream function receives the malicious path from the source inventory.
7. The FilesystemTarget.WriteStream function joins the attacker-controlled path with the target root path.
8. The file outside.txt is created (or overwritten) outside Alice’s specified target directory, with Alice’s credentials.

Impact

Successful exploitation of CVE-2026-45576 allows a malicious user with access to a zrok share to traverse the directory tree arbitrarily on the system where the zrok copy command is executed. This can lead to the overwriting of sensitive information, potentially causing data loss, system instability, or privilege escalation if critical system files are targeted. The number of victims and the scope of impact depend on the privileges of the user running zrok copy and the contents of the files that are overwritten.

Recommendation

• Upgrade to zrok/v2 version 2.0.3 or later to patch CVE-2026-45576.
• Upgrade zrok versions between 0.4.23 and 1.1.11 (inclusive) to a patched version.
• Monitor file creation events for unexpected write operations outside the intended target directory using a file integrity monitoring system, and deploy the provided Sigma rules.