Your upload validation is probably broken

import pypdf
from PIL import Image
import openpyxl
import pyclamd
import os, csv, json

def validate_file(path):
    ext = os.path.splitext(path)[1].lower()
    size = os.path.getsize(path)

    if size == 0:
        return "CORRUPT: empty file"

    if ext == ".pdf":
        try:
            reader = pypdf.PdfReader(path)
            text = ""
            for page in reader.pages:
                text += page.extract_text() or ""
            if not any(len(w) >= 3 for w in text.split()):
                return "BLANK: no readable content"
        except Exception:
            return "CORRUPT: invalid PDF"

    elif ext in (".png", ".jpg", ".jpeg"):
        try:
            img = Image.open(path)
            img.verify()
            img = Image.open(path)
            colors = img.getcolors(maxcolors=1)
            if colors and len(colors) == 1:
                return "BLANK: single-color image"
        except Exception:
            return "CORRUPT: invalid image"

    elif ext == ".xlsx":
        try:
            wb = openpyxl.load_workbook(path)
            has_data = False
            for ws in wb.worksheets:
                for row in ws.iter_rows(max_row=100):
                    if any(c.value for c in row):
                        has_data = True
                        break
            if not has_data:
                return "BLANK: no data rows"
        except Exception:
            return "CORRUPT: invalid spreadsheet"

    # ... repeat for CSV, DOCX, JSON, XML,
    #     ZIP, MP3, MP4, TXT ...

    # Virus scanning
    try:
        cd = pyclamd.ClamdNetworkSocket()
        result = cd.scan_file(path)
        if result:
            return f"VIRUS: {result}"
    except Exception:
        pass  # ClamAV not available

    return "PASS"