CVE-2026-77814: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in zanllp infinite-image-browsing

The vulnerability arises from the is_path_trusted function in scripts/iib/api.py, which uses path.startswith(parent_path) without appending a path separator, causing directories with names beginning with allowed paths to be mistakenly trusted. For example, if /data/images is allowed, a request for /data/images_private/secret.txt is incorrectly served, disclosing unauthorized files. Access control depends on the get_enable_access_control function, which returns true or false based on environment variables and startup options. The issue is fixed by comparing against parent_path joined with os.sep to ensure exact directory matching.

An attacker can exploit this flaw to access and disclose files outside the intended restricted directories, potentially exposing sensitive information. This affects network-exposed WebUI deployments that rely on the access control mechanism. Standalone runs without these options serve all readable files regardless of the flaw, increasing exposure. The CVSS 4.0 score is 8.7 (high severity), indicating a significant risk of unauthorized file disclosure without requiring privileges or user interaction.

A fix is available that corrects the path validation by appending the path separator to parent_path before comparison. Users should upgrade to a version that includes this fix. Since no explicit patch link is provided, check the vendor's advisory or repository for the updated version. Until patched, avoid exposing the WebUI with network options that enable access control or restrict access to trusted users only.