ZLMediaKit Download File API server/WebApi.cpp downloadFile relative-path path traversal

Summaryinfo

A vulnerability, which was classified as problematic, has been found in ZLMediaKit. Affected by this vulnerability is the function downloadFile of the file server/WebApi.cpp of the component Download File API. The manipulation of the argument relative-path leads to path traversal. This vulnerability is traded as CVE-2026-81028. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in ZLMediaKit (affected version unknown) and classified as problematic. This issue affects the function downloadFile of the file server/WebApi.cpp of the component Download File API. The manipulation of the argument relative-path with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is confidentiality. The summary by CVE is:

ZLMediaKit confines the downloadFile API to a configured set of root directories with a prefix comparison that does not account for directory boundaries. The configuration loader in server/WebApi.cpp builds each root with File::absolutePath("", item, true); because the relative-path argument is empty that helper returns the value without a trailing separator. The handler then accepts a requested path when start_with(file_path, root) holds, so a sibling directory whose name merely begins with the configured root string satisfies the test and is served. The only other guard rejects a path containing two dots, which this requires none of. The equivalent confinement check for the ordinary static file server in src/Http/HttpFileManager.cpp computes its root with a non-empty second argument, which appends the separator before comparing, and so is not affected. The endpoint requires the configured API secret, so this grants no privilege beyond what that secret already implies, but it reads files outside the directory the operator confined it to, and the reference container runs the server as root.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-81028 since 08/26/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

Applying the patch fa347d7dbe48dfdce525d3a0fdb92e576970ef9f is able to eliminate this problem.

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• ZLMediaKit

CPE 2.3info

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CPE 2.2info

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