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What is CVE-2020-3580?A medium-severity flaw criminals are using now.

Medium severityKnown exploited2 affected products
The short answer

CVE-2020-3580 is a medium-severity flaw (CVSS 6.1) in Firepower Threat Defense from Cisco, published on 21 October 2020. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 86%. If you run an affected version, patch it first.

Check if it affects you →How to fix it

Published 21 October 2020. Record last updated 28 October 2025. We keep this page's data up to date.

What it does

What is CVE-2020-3580? In plain terms.

It can be attacked from anywhere on the internet without logging in, but a person has to take an action first. If it works, the attacker can read some data and change some data.

The official description

Multiple vulnerabilities in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to conduct cross-site scripting (XSS) attacks against a user of the web services interface of an affected device. The vulnerabilities are due to insufficient validation of user-supplied input by the web services interface of an affected device. An attacker could exploit these vulnerabilities by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the interface or allow the attacker to access sensitive, browser-based information. Note: These vulnerabilities affect only specific AnyConnect and WebVPN configurations. For more information, see the Vulnerable Products section.

What kind of flaw is it?

  • CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS 3.1 scoreMedium · 6.1

How an attack on it works

Read straight from its severity rating, translated out of the shorthand.

  • Where an attacker can beAnywhere on the internet
  • How hard it is to pull offEasy: no special conditions
  • Login needed firstNo login needed
  • Does someone have to clickYes, a person has to take an action
  • What an attacker getsCan read some data and change some data

Severity vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploitation

Is CVE-2020-3580 being exploited? Yes.

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 86%.

Known to be exploitedYesOn the government list of exploited flaws
Chance of use in the next 30 days86%Its EPSS score, from the latest forecast

Timeline

  1. Published
  2. Record last updated
How Precursor Intelligence ranks it
81out of 100High

CVE-2020-3580 scores 81. Action: Emergency patch.

We keep the score of every published flaw up to date as the evidence changes. Four things go into the score, and evidence that criminals are actually using it counts most. In order:

  • Evidence it is being exploitedBiggest factor
  • How severe it isStrong factor
  • How widely exposed it isSmaller factor
  • Threat activity around itSmaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.

When CVE-2020-3580 matches software you track, it lands in your list with its score and the reasons behind it.

See your own ranked list →
Affected products

Who is affected by CVE-2020-3580? 2 products.

The published record lists 2 products from 1 vendor. Versions are shown as published: "before 6.4.0.12" means every version up to, but not including, 6.4.0.12. If you run one of these, check your version, then go to the fix below.

Remediation

How do I fix CVE-2020-3580? Four steps.

  1. Check whether you run itCompare 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 fixInstall the update named in the vendor’s advisory. We’ve put the advisory first in the list.
  3. If you can’t patch todayFollow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
  4. Check it wasn’t used before you patchedBecause criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

References

2 links
Precursor Intelligence

Does CVE-2020-3580 affect you? We'll keep checking.

Looking flaws up one at a time doesn't scale. Tell us what you run once, and we tell you which flaws matter to you, in what order, and keep watching for new ones.

  1. Tell us what you runPick your software from a list, or let us work it out from your website.
  2. We match it to every flawOver 400,000 published flaws, checked against your list.
  3. Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
  4. Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
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FAQ

Common questions, answered plainly.

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CVE-2020-3580 is a medium-severity flaw in Firepower Threat Defense from Cisco, published on 21 October 2020. It can be attacked from anywhere on the internet without logging in, but a person has to take an action first. If it works, the attacker can read some data and change some data.

It scores 6.1 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2020-3580 is 81 out of 100, which is High. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 86%.

For Firepower Threat Defense from Cisco: before 6.4.0.12, 6.5.0 to before 6.6.4, 6.7.0 to before 6.7.0.2. The record lists 2 products in all, each with its versions, under "Who is affected" on this page.

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. Because criminals are already using it, also check affected systems for signs of a break-in.

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