diff --git a/routes/gallery_routes.py b/routes/gallery_routes.py
index db17bfe..a250211 100644
--- a/routes/gallery_routes.py
+++ b/routes/gallery_routes.py
@@ -3,6 +3,9 @@
 import os
 import hashlib
 import logging
+import re
+import uuid
+from pathlib import Path
 from typing import Dict, Any, Optional
 
 from fastapi import APIRouter, HTTPException, Query, Request
@@ -17,6 +20,14 @@ from routes.gallery_helpers import (
 
 logger = logging.getLogger(__name__)
 
+
+def _sanitize_gallery_filename(filename: str) -> str:
+    """Return a local filename safe to join under generated_images."""
+    safe_name = re.sub(r"[^A-Za-z0-9._-]", "_", Path(filename or "").name)[:128]
+    if not safe_name or safe_name in {".", ".."}:
+        safe_name = uuid.uuid4().hex[:12]
+    return safe_name
+
 def setup_gallery_routes() -> APIRouter:
     router = APIRouter(tags=["gallery"])
 
@@ -122,7 +133,7 @@ def setup_gallery_routes() -> APIRouter:
             content = await file.read()
             img_dir = Path("data/generated_images")
             img_dir.mkdir(parents=True, exist_ok=True)
-            img_path = img_dir / img.filename
+            img_path = img_dir / _sanitize_gallery_filename(img.filename)
             img_path.write_bytes(content)
 
             # Refresh dimensions in case the editor resized the canvas.
diff --git a/routes/session_routes.py b/routes/session_routes.py
index 6533444..e524791 100644
--- a/routes/session_routes.py
+++ b/routes/session_routes.py
@@ -14,6 +14,13 @@ from core.database import Session as DbSession, SessionLocal, Document, GalleryI
 from src.auth_helpers import get_current_user, effective_user
 
 
+def _sanitize_export_filename(name: str) -> str:
+    """Return a conservative filename safe for Content-Disposition."""
+    name = name or ""
+    name = re.sub(r"[^A-Za-z0-9._-]", "_", name)
+    return name[:128]
+
+
 def _verify_session_owner(request: Request, session_id: str):
     """Verify the current user owns the session. Raises 404 if not."""
     user = effective_user(request)
@@ -558,6 +565,7 @@ def setup_session_routes(session_manager: SessionManager, config: dict, webhook_
 
         safe_name = re.sub(r'[^\w\-_]', '_', session.name)
         timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
+        filename = _sanitize_export_filename(filename)
 
         if fmt == "json":
             import json as _json
diff --git a/tests/test_security_regressions.py b/tests/test_security_regressions.py
index 6b3a691..1f8e397 100644
--- a/tests/test_security_regressions.py
+++ b/tests/test_security_regressions.py
@@ -943,6 +943,85 @@ def test_mcp_oauth_page_escapes_reflected_values():
         assert f"{var} = html.escape({var}" in body, var
 
 
+
+# -- export/gallery filename hardening ----------------------------------------
+
+def _install_route_import_stubs(monkeypatch):
+    core_mod = types.ModuleType("core")
+    core_mod.__path__ = []
+
+    db_mod = types.ModuleType("core.database")
+    db_mod.SessionLocal = lambda: None
+    for name in (
+        "Session",
+        "Document",
+        "GalleryImage",
+        "GalleryAlbum",
+        "ModelEndpoint",
+    ):
+        setattr(db_mod, name, type(name, (), {}))
+
+    session_manager_mod = types.ModuleType("core.session_manager")
+    session_manager_mod.SessionManager = type("SessionManager", (), {})
+
+    models_mod = types.ModuleType("core.models")
+    models_mod.ChatMessage = type("ChatMessage", (), {})
+
+    monkeypatch.setitem(sys.modules, "core", core_mod)
+    monkeypatch.setitem(sys.modules, "core.database", db_mod)
+    monkeypatch.setitem(sys.modules, "core.session_manager", session_manager_mod)
+    monkeypatch.setitem(sys.modules, "core.models", models_mod)
+
+
+def _import_session_routes_for_filename(monkeypatch):
+    _install_route_import_stubs(monkeypatch)
+    monkeypatch.delitem(sys.modules, "routes.session_routes", raising=False)
+    from routes import session_routes
+    return session_routes
+
+
+def _import_gallery_routes_for_filename(monkeypatch):
+    _install_route_import_stubs(monkeypatch)
+    monkeypatch.delitem(sys.modules, "routes.gallery_helpers", raising=False)
+    monkeypatch.delitem(sys.modules, "routes.gallery_routes", raising=False)
+    from routes import gallery_routes
+    return gallery_routes
+
+
+def test_export_filename_sanitizer_blocks_header_and_path_chars(monkeypatch):
+    mod = _import_session_routes_for_filename(monkeypatch)
+
+    out = mod._sanitize_export_filename('chat.md\r\nX-Test: yes/..\\evil;quote".txt\x00')
+
+    assert out
+    assert len(out) <= 128
+    for ch in '\r\n/\\:\x00;" ':
+        assert ch not in out
+
+
+def test_export_filename_sanitizer_preserves_safe_names(monkeypatch):
+    mod = _import_session_routes_for_filename(monkeypatch)
+
+    assert mod._sanitize_export_filename("conversation_20260602.md") == "conversation_20260602.md"
+    assert mod._sanitize_export_filename("") == ""
+
+
+def test_gallery_replace_filename_sanitizer_uses_basename(monkeypatch):
+    mod = _import_gallery_routes_for_filename(monkeypatch)
+
+    out = mod._sanitize_gallery_filename("../../etc/cron.d/evil image.png")
+
+    assert out == "evil_image.png"
+    assert "/" not in out
+    assert "\\" not in out
+
+
+def test_gallery_replace_filename_sanitizer_falls_back_when_empty(monkeypatch):
+    mod = _import_gallery_routes_for_filename(monkeypatch)
+    monkeypatch.setattr(mod.uuid, "uuid4", lambda: types.SimpleNamespace(hex="abcdef1234567890"))
+
+    assert mod._sanitize_gallery_filename("../") == "abcdef123456"
+
 def test_chat_active_document_lookup_is_owner_scoped():
     """The explicit `active_doc_id` path in /api/chat_stream must scope the
     document lookup to the caller. Resolving by id alone let any user inject