diff --git a/swh/fuse/fs/artifact.py b/swh/fuse/fs/artifact.py
--- a/swh/fuse/fs/artifact.py
+++ b/swh/fuse/fs/artifact.py
@@ -21,6 +21,8 @@
 from swh.model.from_disk import DentryPerms
 from swh.model.identifiers import CONTENT, DIRECTORY, RELEASE, REVISION, SNAPSHOT, SWHID
 
+SWHID_REGEXP = r"swh:1:(cnt|dir|rel|rev|snp):[0-9a-f]{40}"
+
 
 @dataclass
 class Content(FuseFileEntry):
@@ -257,6 +259,7 @@
     is_status_done: bool = field(default=False)
 
     DATE_FMT = "{year:04d}/{month:02d}/{day:02d}/"
+    ENTRIES_REGEXP = r"^(([0-9]{2,4})" + f"|({SWHID_REGEXP}))$"
 
     @dataclass
     class StatusFile(FuseFileEntry):
@@ -324,6 +327,7 @@
     prefix: str = field(default="")
 
     SHARDING_LENGTH = 2
+    ENTRIES_REGEXP = r"^([a-f0-9]+)" + f"|({SWHID_REGEXP})$"
 
     async def compute_entries(self) -> AsyncIterator[FuseEntry]:
         history = await self.fuse.get_history(self.history_swhid)
@@ -362,6 +366,7 @@
 
     PAGE_SIZE = 10_000
     PAGE_FMT = "{page_number:03d}"
+    ENTRIES_REGEXP = r"^([0-9]+)" + f"|({SWHID_REGEXP})$"
 
     async def compute_entries(self) -> AsyncIterator[FuseEntry]:
         history = await self.fuse.get_history(self.history_swhid)
@@ -532,6 +537,7 @@
     node. """
 
     DATE_FMT = "{year:04d}-{month:02d}-{day:02d}"
+    ENTRIES_REGEXP = r"^[0-9]{4}-[0-9]{2}-[0-9]{2}$"
 
     async def compute_entries(self) -> AsyncIterator[FuseEntry]:
         # The origin's name is always its URL (encoded to create a valid UNIX filename)
diff --git a/swh/fuse/fs/entry.py b/swh/fuse/fs/entry.py
--- a/swh/fuse/fs/entry.py
+++ b/swh/fuse/fs/entry.py
@@ -8,6 +8,7 @@
 from dataclasses import dataclass, field
 from enum import IntEnum
 from pathlib import Path
+import re
 from stat import S_IFDIR, S_IFLNK, S_IFREG
 from typing import Any, AsyncIterator, Sequence, Union
 
@@ -60,6 +61,7 @@
         return constructor(depth=self.depth + 1, fuse=self.fuse, **kwargs)
 
 
+@dataclass
 class FuseFileEntry(FuseEntry):
     """ FUSE virtual file entry """
 
@@ -72,12 +74,21 @@
         return len(await self.get_content())
 
 
+@dataclass
 class FuseDirEntry(FuseEntry):
     """ FUSE virtual directory entry """
 
+    ENTRIES_REGEXP: str = field(init=False, default="")
+
     async def size(self) -> int:
         return 0
 
+    def validate_entry(self, name: str) -> bool:
+        """ Return true if the name matches the directory entries regular
+        expression, and false otherwise """
+
+        return re.match(self.ENTRIES_REGEXP, name)
+
     async def compute_entries(self) -> Sequence[FuseEntry]:
         """ Return the child entries of a directory entry """
 
@@ -101,6 +112,9 @@
     async def lookup(self, name: str) -> FuseEntry:
         """ Look up a FUSE entry by name """
 
+        if not self.validate_entry(name):
+            return None
+
         async for entry in self.get_entries():
             if entry.name == name:
                 return entry
diff --git a/swh/fuse/fs/mountpoint.py b/swh/fuse/fs/mountpoint.py
--- a/swh/fuse/fs/mountpoint.py
+++ b/swh/fuse/fs/mountpoint.py
@@ -7,7 +7,7 @@
 import json
 from typing import AsyncIterator
 
-from swh.fuse.fs.artifact import OBJTYPE_GETTERS, Origin
+from swh.fuse.fs.artifact import OBJTYPE_GETTERS, SWHID_REGEXP, Origin
 from swh.fuse.fs.entry import EntryMode, FuseDirEntry, FuseEntry, FuseFileEntry
 from swh.model.exceptions import ValidationError
 from swh.model.identifiers import CONTENT, SWHID, parse_swhid
@@ -38,6 +38,7 @@
     name: str = field(init=False, default="archive")
     mode: int = field(init=False, default=int(EntryMode.RDONLY_DIR))
 
+    ENTRIES_REGEXP = f"^({SWHID_REGEXP})(.json)?$"
     JSON_SUFFIX = ".json"
 
     async def compute_entries(self) -> AsyncIterator[FuseEntry]:
@@ -45,6 +46,9 @@
         yield
 
     async def lookup(self, name: str) -> FuseEntry:
+        if not self.validate_entry(name):
+            return None
+
         # On the fly mounting of a new artifact
         try:
             if name.endswith(self.JSON_SUFFIX):
@@ -100,6 +104,8 @@
     name: str = field(init=False, default="origin")
     mode: int = field(init=False, default=int(EntryMode.RDONLY_DIR))
 
+    ENTRIES_REGEXP = r"^.*%3A.*$"  # %3A is the encoded version of ':'
+
     def create_child(self, url_encoded: str) -> FuseEntry:
         return super().create_child(
             Origin, name=url_encoded, mode=int(EntryMode.RDONLY_DIR),
@@ -110,6 +116,9 @@
             yield self.create_child(url)
 
     async def lookup(self, name: str) -> FuseEntry:
+        if not self.validate_entry(name):
+            return None
+
         entry = await super().lookup(name)
         if entry:
             return entry