langchain-ai/deepagents · error · ValueError

Permission path must not contain '..': {path!r}

Error message

Permission path must not contain '..': {path!r}

What it means

FilesystemPermission patterns must not contain '..' path segments; parent-directory traversal would make permission rules ambiguous or let rules escape their intended tree. Violating patterns raise this ValueError in __post_init__.

Source

Thrown at libs/deepagents/deepagents/middleware/filesystem.py:417

        Best paired with patterns that have a literal leading anchor (e.g.,
        `/secrets/**`, `/projects/*/secrets/**`). Bulk tools
        (`ls`/`glob`/`grep`) fire the interrupt based on whether their
        search subtree could overlap the rule's anchored prefix, so a fully
        unanchored pattern (`/**/secrets`) collapses to `/` and
        conservatively over-fires for any bulk call.
    """

    def __post_init__(self) -> None:
        """Validate permission path patterns."""
        for path in self.paths:
            if not path.startswith("/"):
                msg = f"Permission path must start with '/': {path!r}"
                raise ValueError(msg)
            parts = PurePosixPath(path.replace("\\", "/")).parts
            if ".." in parts:
                msg = f"Permission path must not contain '..': {path!r}"
                raise ValueError(msg)
            if "~" in parts:
                msg = f"Permission path must not contain '~': {path!r}"
                raise NotImplementedError(msg)


def _check_fs_permission(
    rules: list[FilesystemPermission],
    operation: FilesystemOperation,
    path: str,
) -> Literal["allow", "deny", "interrupt"]:
    for rule in rules:
        if operation not in rule.operations:
            continue
        if any(wcglob.globmatch(path, pattern, flags=_FS_WCMATCH_FLAGS) for pattern in rule.paths):
            return rule.mode
    return "allow"

View on GitHub (pinned to a1af029e6e)

Solutions

1. Remove '..' by normalizing/resolving the path (os.path.normpath or posixpath.normpath) before building the pattern
2. Express the intended target directly without traversal segments
3. Sanitize user input to reject traversal attempts early

Example fix

// before
FilesystemPermission(paths=["/project/../secrets"])
// after
FilesystemPermission(paths=["/secrets"])

import posixpath
def ensure_no_dotdot(p: str) -> str:
    normalized = posixpath.normpath(p)
    if ".." in posixpath.normpath(p).split("/"):
        raise ValueError(f"permission path must not contain '..': {p!r}")
    return normalized

try:
    perm = FilesystemPermission(paths=paths)
except ValueError as e:
    logger.error("traversal in permission pattern: %s", e)
    raise

When it happens

Trigger: Constructing FilesystemPermission with a pattern like '/a/../etc' or '/..' — after converting backslashes, '..' appears in PurePosixPath parts.

Common situations: Concatenating user-supplied path fragments without normalization; porting Windows-style relative patterns; generated patterns from templates that inject '..'.

Related errors

• interpreter_ptc='all' exposes every host tool to PTC calls t
• temporary artifact is not a regular file
• Path traversal not allowed
• Permission path must start with '/': {path!r}
• read_file must be included in tools; it is required by Files

AI-assisted analysis of langchain-ai/deepagents@a1af029e6e (2026-08-29). Data as JSON: /api/errors/9af7c23bd4d28d4a. Report an issue: GitHub.