system: You are an expert security code reviewer. You will be shown a source code file along with a catalog of candidate CWE (Common Weakness Enumeration) categories with their official MITRE names. Your task is to list every distinct CWE from that catalog that is actually present in the code. The catalog is comprehensive for this dataset -- the answer is a (possibly small) subset of it.

OUTPUT FORMAT: Respond with a comma-separated list of CWE IDs in the form `CWE-N`, sorted in ascending numeric order, wrapped in a single \boxed{...}. Examples: `\boxed{CWE-79}` for one, `\boxed{CWE-22,CWE-79,CWE-327}` for three. Output the boxed answer ONLY -- no explanation, no other text.

user: ```python
#! /usr/bin/env python

# Title:        TickTock
# Description:  Enumerate user names through observing and comparing response time delays from a web server.
# Author:       NulledByte
# Version:      1.0
# Date:         2014-02-11
# License:      MIT License

from __future__ import division
import argparse
import pycurl
import matplotlib.pyplot as plt
import logging
import statistics

from decimal import getcontext
from io import BytesIO

try:
    from urllib.parse import urlencode
except ImportError:
    from urllib import urlencode

LOG_FILENAME = "ticktock.log"
logging.basicConfig(level=logging.DEBUG,
                    format='%(asctime)s %(levelname)-8s %(message)s',
                    datefmt='%m-%d %H:%M',)


# Configure arguments for the Python script.
parser = argparse.ArgumentParser(description='Identify username timing attacks')
parser.add_argument('--target', help='The login page')
parser.add_argument('--valid_post', help='The POST data for a valid user')
parser.add_argument('--invalid_post', help='The POST data for an invalid user')
parser.add_argument('--attempts', help="The number of authentication attempts to process.", default=50, type=int)
parser.add_argument('--time_delay', help="The time in milliseconds between authentication requests", default=50, type=int)
parser.add_argument('--precision', help="The precision when rounding.", default=3, type=int)
args = parser.parse_args()

logging.debug("Passed arguments: {0}".format(args))

# Decimal precision
getcontext().prec = 4


def send_request(target, data, method='POST'):
    """
    Create a native CURL HTTP connection to the site, and POST the data. Return the timing information.
    :type target: str
    :type data: str
    :type method: str
    :return:
    """

    # Store the HTTP response
    buffer = BytesIO()

    curl = pycurl.Curl()

    # Remove this!
    curl.setopt(pycurl.SSL_VERIFYPEER, 0)
    curl.setopt(pycurl.SSL_VERIFYHOST, 0)

    curl.setopt(pycurl.URL, target)
    curl.setopt(pycurl.POSTFIELDS, data)
    curl.setopt(pycurl.WRITEDATA, buffer)
    curl.perform()

    return curl


def extract_timings(request, precision):

    """
    Retrieve the timings for each stage of the HTTP communication and store them as a rounded value
    :type request: pycurl.Curl
    :type precision: int
    :return: dict
    """

    transfer = {
        'DNSLookup': round(request.getinfo(pycurl.NAMELOOKUP_TIME), precision),
        'TCPConnectionTime': round(request.getinfo(pycurl.CONNECT_TIME), precision),
        'AppConnectionTine': round(request.getinfo(pycurl.APPCONNECT_TIME), precision),
        'StartTransferTime': round(request.getinfo(pycurl.STARTTRANSFER_TIME), precision),
        'TotalTime': round(request.getinfo(pycurl.TOTAL_TIME), precision)
    }

    return transfer

metrics = {"valid": list(), "invalid": list()}

for i in range(args.attempts):

    # Issue the Curl requests for both invalid and valid usernames
    valid_handle = send_request(args.target, args.valid_post)
    valid_results = extract_timings(valid_handle, args.precision)
    valid_handle.close()

    invalid_handle = send_request(args.target, args.invalid_post)
    invalid_results = extract_timings(invalid_handle, args.precision)
    invalid_handle.close()

    logging.debug("Processed {0} / {1} requests...".format(i, args.attempts))

    metrics['valid'].append(valid_results)
    metrics['invalid'].append(invalid_results)

# Generate the data lists for the plotting library
y_axis_valid = [metric['StartTransferTime'] / metric['TotalTime'] for metric in metrics['valid']]
y_axis_invalid = [metric['StartTransferTime'] / metric['TotalTime'] for metric in metrics['invalid']]

logging.info("Valid login response average: {0}".format(statistics.mean(y_axis_valid)))
logging.info("Invalid login response average: {0}".format(statistics.mean(y_axis_invalid)))

# Generate a sequential list, representing the request number for the x axis
x_axis = range(1, args.attempts + 1)

# General graph options and format
plt.title("Response Times for Valid / Invalid User Names")
plt.ylabel('Response Time (ms)')
plt.xlabel('Request Number (#)')
plt.minorticks_on()

# Plot all the results with color (invalid=red, valid=blue)
plt.plot(x_axis, y_axis_valid, 'b')
plt.plot(x_axis, y_axis_invalid, 'r')

# Manually set the axis scale to have a 5% buffer and show the graph
plt.axis([1, args.attempts,
          min(y_axis_valid) - (min(y_axis_valid) * 0.05),
          max(y_axis_valid) + (max(y_axis_valid) * 0.05)])

plt.show()

```

Candidate CWE catalog (every CWE that appears anywhere in this dataset):
  - CWE-20: Improper Input Validation
  - CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
  - CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
  - CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
  - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
  - CWE-89: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
  - CWE-94: Improper Control of Generation of Code ('Code Injection')
  - CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
  - CWE-116: Improper Encoding or Escaping of Output
  - CWE-117: Improper Output Neutralization for Logs
  - CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
  - CWE-209: Generation of Error Message Containing Sensitive Information
  - CWE-215: Insertion of Sensitive Information Into Debugging Code
  - CWE-295: Improper Certificate Validation
  - CWE-312: Cleartext Storage of Sensitive Information
  - CWE-326: Inadequate Encryption Strength
  - CWE-327: Use of a Broken or Risky Cryptographic Algorithm
  - CWE-377: Insecure Temporary File
  - CWE-502: Deserialization of Untrusted Data
  - CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
  - CWE-611: Improper Restriction of XML External Entity Reference
  - CWE-614: Sensitive Cookie in HTTPS Session Without 'Secure' Attribute
  - CWE-643: Improper Neutralization of Data within XPath Expressions ('XPath Injection')
  - CWE-730: OWASP Top Ten 2004 Category A9 - Denial of Service
  - CWE-732: Incorrect Permission Assignment for Critical Resource
  - CWE-776: Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
  - CWE-918: Server-Side Request Forgery (SSRF)
  - CWE-943: Improper Neutralization of Special Elements in Data Query Logic
  - CWE-1004: Sensitive Cookie Without 'HttpOnly' Flag
  - CWE-1333: Inefficient Regular Expression Complexity

List every distinct CWE from the catalog above that is actually present in this code.
Answer: CWE-295