# CVE-2025-20333: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow

> Authenticated remote attackers can execute arbitrary code as root on Cisco ASA and FTD devices via crafted HTTP requests, leading to full device compromise.

- **Severity:** Critical 9.9 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 25 Sep 2025 (CISA KEV)
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Sep 2025
- **Updated:** 26 Feb 2026
- **Also known as:** GHSA-vg93-6w2x-3cvp

## What is CVE-2025-20333?

CVE-2025-20333 is a critical code injection vulnerability in Cisco Adaptive Security Appliance Software, published on 25 Sep 2025. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to execute arbitrary code on an affected device.

 This vulnerability is due to improper validation of user-supplied input in HTTP(S) requests. An attacker with valid VPN user credentials could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute arbitrary code as root, possibly resulting in the complete compromise of the affected device.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2025-20333?

It affects 2 products.


Products: Cisco Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense.

## How do I fix CVE-2025-20333?

No fix has been published for CVE-2025-20333 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 26 Sep 2025.

## Is CVE-2025-20333 being exploited?

Yes. Attackers have exploited CVE-2025-20333 in the wild since at least 25 Sep 2025.

Public exploit code:

- Safe Python scanner for Cisco CVE-2025-20333 (Cisco ASA/FTD WebVPN Buffer Overflow) (github_poc): https://github.com/curtishoughton/Cisco-ASA-CVE-2025-20333-Scanner
- Cisco ASA vulnerability research CVE-2025-20333/CVE-2025-20362 (github_poc): https://github.com/cobbbex/Cisco-ASA-vulnerability-research
- https://github.com/cobbbex/cve-2025-20333 (github_poc): https://github.com/cobbbex/cve-2025-20333

## Other vulnerabilities in Cisco Adaptive Security Appliance Software

- [CVE-2016-6366](https://insights.sbomify.com/CVE-2016-6366/): Cisco Adaptive Security Appliance (ASA) SNMP Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2026-20349](https://insights.sbomify.com/CVE-2026-20349/): Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection (high 8.6, exploited in the wild)
- [CVE-2024-20353](https://insights.sbomify.com/CVE-2024-20353/): Cisco ASA and FTD Denial of Service (high 8.6, exploited in the wild)
- [CVE-2016-6367](https://insights.sbomify.com/CVE-2016-6367/): Cisco Adaptive Security Appliance (ASA) CLI Remote Code Execution (high 7.8, exploited in the wild)
- [CVE-2020-3452](https://insights.sbomify.com/CVE-2020-3452/): Cisco ASA and FTD Read-Only Path Traversal (high 7.5, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-20333 and fix it if it is affected.

What it is: CVE-2025-20333 is a critical code injection vulnerability in Cisco Adaptive Security Appliance Software, published on 25 Sep 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2025-20333 in the wild since at least 25 Sep 2025.

Affected product: Cisco Adaptive Security Appliance Software. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-20333/ (Markdown: https://insights.sbomify.com/CVE-2025-20333/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-20333
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-20333
- OSV: https://osv.dev/vulnerability/CVE-2025-20333

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-20333/
Summaries are generated and may contain mistakes; the official description above is the record.