fix: harden /files/upload path handling for multi-user isolation

- Resolve directory parameter through fs.resolve_path()
- Sanitize uploaded filename with os.path.basename()
- Normalize composed path with os.path.normpath()
- Catch PermissionError and return 403 for cross-user access attempts

Author: tjbck

CHANGELOG.md

@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## [0.11.11] - 2026-03-11
+
+### Fixed
+
+- 🔒 **Upload path traversal** — `/files/upload` now resolves the `directory` parameter through `fs.resolve_path()` and sanitizes the uploaded filename with `os.path.basename()`, preventing path traversal attacks (e.g. `../../etc/passwd`) that could escape the user's home directory in multi-user mode. The composed path is normalized with `os.path.normpath()` and validated by `_check_path` before writing. All other file endpoints already had these protections.
+
 ## [0.11.10] - 2026-03-11
 
 ### Fixed

open_terminal/main.py

@@ -878,16 +878,20 @@ async def upload_file(
         filename = os.path.basename(urlparse(url).path) or "download"
     elif file:
         content = await file.read()
-        filename = file.filename or "upload"
+        filename = os.path.basename(file.filename or "upload")
     else:
         raise HTTPException(
             status_code=400, detail="Provide either 'url' or a file upload."
         )
 
+    directory = fs.resolve_path(directory)
+    path = os.path.normpath(os.path.join(directory, filename))
+
     try:
         await fs.mkdir(directory)
-        path = os.path.join(directory, filename)
         await fs.write_bytes(path, content)
+    except PermissionError as e:
+        raise HTTPException(status_code=403, detail=str(e))
     except OSError as e:
         raise HTTPException(status_code=400, detail=str(e))
     return {"path": path, "size": len(content)}

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "open-terminal"
-version = "0.11.10"
+version = "0.11.11"
 description = "A remote terminal API."
 readme = "README.md"
 authors = [