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wtf is cisco-asa-cve-2025-20333-scanner?

curtishoughton/cisco-asa-cve-2025-20333-scanner — explained in plain English

Analysis updated 2026-05-18

0PythonAudience · ops devopsComplexity · 2/5Setup · easy

TL;DR

A Python scanner that safely checks if Cisco ASA or FTD devices are exposed to the critical CVE-2025-20333 buffer overflow flaw.

Mindmap

mindmap
  root((CVE-2025-20333 Scanner))
    What it does
      Checks Cisco ASA/FTD exposure
      Safe GET only requests
    Tech stack
      Python
    Use cases
      Vulnerability check
      Security assessment
      Authorized testing
    Audience
      Security researchers
      System administrators

Code map

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filefunction / class

Why would anyone build with this?

REASON 1

Check if Cisco ASA or FTD devices you manage are exposed to CVE-2025-20333.

REASON 2

Run a safe, non-destructive reachability check before deciding to patch or investigate further.

REASON 3

Use as a starting point in a security assessment of Cisco WebVPN endpoints you are authorized to test.

What's in the stack?

Python

How it stacks up

curtishoughton/cisco-asa-cve-2025-20333-scanner0xhassaan/nn-from-scratch3ks/embedoc
Stars00
LanguagePythonPythonPython
Last pushed2023-06-08
MaintenanceDormant
Setup difficultyeasymoderatehard
Complexity2/54/51/5
Audienceops devopsdeveloperdeveloper

Figures from each repo's GitHub metadata at analysis time.

How do you spin it up?

Difficulty · easy Time to first run · 5min

For use only against systems you are authorized to test.

Wtf does this do

This is a Python tool designed to help security professionals check whether a specific critical vulnerability exists on Cisco network devices they are authorized to test. The vulnerability, CVE-2025-20333, is a heap based buffer overflow in the WebVPN file upload handler found in Cisco Secure ASA and Cisco Secure FTD devices. A buffer overflow is a type of memory corruption flaw that happens when a program writes more data into a memory region than it can hold, and in severe cases this lets an attacker run their own code on the affected machine. Here, the potential impact is remote code execution as root, meaning a successful attacker could take full control of the device. The severity is rated 9.9 on the CVSS scale, placing it in the critical category. The scanner works by sending safe, read only GET requests to the WebVPN endpoints associated with this vulnerability. It does not attempt any actual exploitation, it only checks whether vulnerable endpoints are reachable and reports clear indicators of potential exposure. It also tests common path traversal and normalization bypass patterns, which are techniques that probe whether a server can be tricked into serving restricted paths. Results appear with colored console output for easy reading. You would use this tool if you are a security researcher, penetration tester, or system administrator responsible for Cisco ASA or FTD devices with WebVPN or AnyConnect enabled. It is explicitly built for authorized testing only, takes the target URL as a command line argument, and is written in Python.

Yoink these prompts

Prompt 1
Explain what CVE-2025-20333 is and why it is rated critical on the CVSS scale.
Prompt 2
Show me how to run this scanner against a target URL and interpret the colored output.
Prompt 3
Walk me through what the path traversal and normalization bypass checks in this scanner are looking for.
Prompt 4
Help me understand the difference between a reachability check and actual exploitation in this tool.

Frequently asked questions

wtf is cisco-asa-cve-2025-20333-scanner?

A Python scanner that safely checks if Cisco ASA or FTD devices are exposed to the critical CVE-2025-20333 buffer overflow flaw.

What language is cisco-asa-cve-2025-20333-scanner written in?

Mainly Python. The stack also includes Python.

How hard is cisco-asa-cve-2025-20333-scanner to set up?

Setup difficulty is rated easy, with roughly 5min to a first successful run.

Who is cisco-asa-cve-2025-20333-scanner for?

Mainly ops devops.

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