# CVE-2018-0101: Use after free in Cisco Adaptive Security Appliance

> Unauthenticated remote attackers can execute arbitrary code or cause a reload via crafted XML packets when the webvpn feature is enabled on Cisco ASA devices.

- **Severity:** Critical 10.0 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Jan 2018
- **Updated:** 2 Dec 2024
- **Also known as:** GHSA-gxj8-6mjh-32m2

## What is CVE-2018-0101?

CVE-2018-0101 is a critical use after free vulnerability in Cisco Adaptive Security Appliance Software, published on 29 Jan 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the Secure Sockets Layer (SSL) VPN functionality of the Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause a reload of the affected system or to remotely execute code. The vulnerability is due to an attempt to double free a region of memory when the webvpn feature is enabled on the Cisco ASA device. An attacker could exploit this vulnerability by sending multiple, crafted XML packets to a webvpn-configured interface on the affected system. An exploit could allow the attacker to execute arbitrary code and obtain full control of the system, or cause a reload of the affected device. This vulnerability affects Cisco ASA Software that is running on the following Cisco products: 3000 Series Industrial Security Appliance (ISA), ASA 5500 Series Adaptive Security Appliances, ASA 5500-X Series Next-Generation Firewalls, ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, ASA 1000V Cloud Firewall, Adaptive Security Virtual Appliance (ASAv), Firepower 2100 Series Security Appliance, Firepower 4110 Security Appliance, Firepower 9300 ASA Security Module, Firepower Threat Defense Software (FTD). Cisco Bug IDs: CSCvg35618.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2018-0101?

It affects 2 products.


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

## How do I fix CVE-2018-0101?

No fix has been published for CVE-2018-0101 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-0101 being exploited?

There is no known exploitation of CVE-2018-0101 in the wild and no public exploit code.

Public exploit code:

- A low interaction honeypot for the Cisco ASA component capable of detecting CVE-2018-0101, a DoS and remote code execution vulnerability. (github_poc): https://github.com/Cymmetria/ciscoasa_honeypot
- https://github.com/1337g/CVE-2018-0101-DOS-POC (github_poc): https://github.com/1337g/CVE-2018-0101-DOS-POC
- Cisco ASA - Crash (PoC) (exploitdb)

## Other vulnerabilities in Cisco Adaptive Security Appliance Software

- [CVE-2025-20333](https://insights.sbomify.com/CVE-2025-20333/): Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow (critical 9.9, exploited in the wild)
- [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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-0101 and fix it if it is affected.

What it is: CVE-2018-0101 is a critical use after free vulnerability in Cisco Adaptive Security Appliance Software, published on 29 Jan 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-0101 in the wild and no public exploit code.

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-2018-0101/ (Markdown: https://insights.sbomify.com/CVE-2018-0101/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-0101
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-0101
- OSV: https://osv.dev/vulnerability/CVE-2018-0101

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-0101/
Summaries are generated and may contain mistakes; the official description above is the record.