CVE-2026-40163: Saltcorn has an Unauthenticated Path Traversal in sync endpoints allows arbitrary file write and directory read

Saltcorn is an extensible, open source, no-code database application builder. Prior to 1.4.5, 1.5.5, and 1.6.0-beta.4, the POST /sync/offline_changes endpoint allows an unauthenticated attacker to create arbitrary directories and write a changes.json file with attacker-controlled JSON content anywhere on the server filesystem. The GET /sync/upload_finished endpoint allows an unauthenticated attacker to list arbitrary directory contents and read specific JSON files. This vulnerability is fixed in 1.4.5, 1.5.5, and 1.6.0-beta.4.