The vulnerability in zanllp infinite-image-browsing (CVE-2026-77814) is due to improper limitation of a pathname to a restricted directory, specifically a path traversal issue. The is_path_trusted function in scripts/iib/api.py uses path.startswith(parent_path) to check if a requested path is within allowed directories but fails to append a path separator. Consequently, directories with names beginning with allowed paths (e.g., /data/images_private when /data/images is allowed) bypass the check, leading to unauthorized file disclosure via FileResponse. Access control depends on the get_enable_access_control function, which activates confinement when IIB_ACCESS_CONTROL is set to enable or when the host Stable Diffusion WebUI is started with network-exposing options (share, ngrok, listen, server_name). Standalone runs without these options do not enforce confinement, exposing all readable files. The fix corrects the check by comparing against parent_path joined with os.sep to ensure exact directory matching.

This vulnerability allows an attacker to access and disclose files outside the intended restricted directories by exploiting the path traversal flaw. In network-exposed deployments with access control enabled, the flaw is active but confinement is enforced, limiting exposure. However, in standalone deployments without access control, all readable files are accessible regardless of the flaw. This can lead to sensitive data disclosure, impacting confidentiality.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The described fix involves modifying the pathname validation to append a path separator when comparing paths, preventing directory name prefix bypass. Until an official fix is available, ensure that access control is enabled (IIB_ACCESS_CONTROL set to enable) and avoid standalone deployments without confinement. Monitor vendor communications for patch releases.