# CVE-2020-3255: Cisco Firepower Threat Defense Software Packet Flood Denial of Service Vulnerability

> Remote attackers can cause denial of service on Cisco Firepower Threat Defense devices by flooding traffic matching block policies, exhausting memory.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 6 May 2020
- **Updated:** 15 Nov 2024
- **Also known as:** GHSA-fwmm-vfgg-4f84

## What is CVE-2020-3255?

CVE-2020-3255 is a high-severity denial of service vulnerability in Cisco Secure Firewall Threat Defense, published on 6 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the packet processing functionality of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to inefficient memory management. An attacker could exploit this vulnerability by sending a high rate of IPv4 or IPv6 traffic through an affected device. This traffic would need to match a configured block action in an access control policy. An exploit could allow the attacker to cause a memory exhaustion condition on the affected device, which would result in a DoS for traffic transiting the device, as well as sluggish performance of the management interface. Once the flood is stopped, performance should return to previous states.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-3255?

It affects 13 products.


Products: Cisco Asa 5505 Firmware, Cisco Asa 5510 Firmware, Cisco Asa 5512-X Firmware, Cisco Asa 5515-X Firmware, Cisco Asa 5520 Firmware, Cisco Asa 5525-X Firmware, Cisco Asa 5540 Firmware, Cisco Asa 5545-X Firmware, Cisco Asa 5550 Firmware, Cisco Asa 5555-X Firmware, Cisco Asa 5580 Firmware, Cisco Asa 5585-X Firmware, Cisco Secure Firewall Threat Defense.

## How do I fix CVE-2020-3255?

No fix has been published for CVE-2020-3255 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-3255 being exploited?

There is no known exploitation of CVE-2020-3255 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Secure Firewall Threat Defense

- [CVE-2020-3179](https://insights.sbomify.com/CVE-2020-3179/): Cisco Firepower Threat Defense Software Generic Routing Encapsulation Tunnel IPv6 Denial of Service Vulnerability (high 8.6)
- [CVE-2020-3189](https://insights.sbomify.com/CVE-2020-3189/): Cisco Firepower Threat Defense Software VPN System Logging Denial of Service Vulnerability (high 8.6)
- [CVE-2020-3283](https://insights.sbomify.com/CVE-2020-3283/): Cisco Firepower 1000 Series SSL/TLS Denial of Service Vulnerability (high 8.6)
- [CVE-2020-3186](https://insights.sbomify.com/CVE-2020-3186/): Cisco Firepower Threat Defense Software Management Access List Bypass Vulnerability (medium 5.3)
- [CVE-2020-3188](https://insights.sbomify.com/CVE-2020-3188/): Cisco Firepower Threat Defense Software Management Interface Denial of Service Vulnerability (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-3255 and fix it if it is affected.

What it is: CVE-2020-3255 is a high-severity denial of service vulnerability in Cisco Secure Firewall Threat Defense, published on 6 May 2020. 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-2020-3255 in the wild and no public exploit code.

Affected product: Cisco Secure Firewall Threat Defense. 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-2020-3255/ (Markdown: https://insights.sbomify.com/CVE-2020-3255/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3255
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3255
- OSV: https://osv.dev/vulnerability/CVE-2020-3255

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-3255/
Summaries are generated and may contain mistakes; the official description above is the record.