# What is CVE-2018-0101?

> CVE-2018-0101 is a critical-severity flaw (CVSS 10.0) in Firepower Threat Defense from Cisco, published on 29 January 2018. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 87%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2018-0101

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **Precursor Intelligence risk score:** 83 out of 100 (High); action: Patch now. Kept up to date as the evidence changes.
- **Severity:** Critical (CVSS 10.0 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 87% (latest exploit-likelihood forecast)
- **Published:** 29 January 2018
- **Record last updated:** 15 August 2023
- **Main product:** Firepower Threat Defense from Cisco
- **Affected products:** 2

## What is CVE-2018-0101? In plain terms

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The 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.

### What kind of flaw is it?

- CWE-415: Double Free

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Easy: no special conditions
- Login needed first: No login needed
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

Severity vector: `CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Is CVE-2018-0101 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 87%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 87%, 87%, 87%, 87%, 87%, 87%, 87%.

### Timeline

- 29 January 2018: Published
- 15 August 2023: Record last updated
- 24 August 2026: Exploit likelihood fell
- 25 August 2026: Exploit likelihood jumped

### How Precursor Intelligence ranks it

CVE-2018-0101 scores **83 out of 100 (High)**, with the action "Patch now".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2018-0101?

The published record lists 2 products. Versions are as published: "before 9.1.7.23" means every version up to, but not including, 9.1.7.23.

- [Firepower Threat Defense](https://www.precursorintelligence.com/product/cisco/firepower_threat_defense) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Application): 6.0.0, 6.0.1, 6.1.0, 6.2.0, 6.2.1, 6.2.2
- [Adaptive Security Appliance Software](https://www.precursorintelligence.com/product/cisco/adaptive_security_appliance_software) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Application): before 9.1.7.23, 9.2.0 to before 9.2.4.27, 9.3.0 to before 9.4.4.16, 9.5.0 to before 9.6.4.3, 9.7.0 to before 9.7.1.21, 9.8.0 to before 9.8.2.20, 9.9.0 to before 9.9.1.2

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

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [tools.cisco.com](https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180129-asa1) (Vendor advisory)
- [securityfocus.com](http://www.securityfocus.com/bid/102845) (Third-party advisory, Vulnerability database)
- [securitytracker.com](http://www.securitytracker.com/id/1040292) (Third-party advisory, Vulnerability database)
- [icanthackit.wordpress.com](https://icanthackit.wordpress.com/2018/01/30/thoughts-on-the-handling-cve-2018-0101-cisco-bug-cscvg35618/) (Third-party advisory)
- [pastebin.com](https://pastebin.com/YrBcG2Ln) (Exploit, Third-party advisory)
- [exploit-db.com](https://www.exploit-db.com/exploits/43986/) (Exploit, Third-party advisory, Vulnerability database)

## Questions

### What is CVE-2018-0101?

CVE-2018-0101 is a critical-severity flaw in Firepower Threat Defense from Cisco, published on 29 January 2018. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2018-0101?

It scores 10.0 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2018-0101 is 83 out of 100, which is High. Its action is "Patch now". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2018-0101 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 87%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2018-0101 affect?

For Firepower Threat Defense from Cisco: 6.0.0, 6.0.1, 6.1.0, 6.2.0, 6.2.1, 6.2.2. The record lists 2 products in all, each with its versions, under "Who is affected" on this page.

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

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

## Does CVE-2018-0101 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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