CVE-2023-20083

What it is

A vulnerability in ICMPv6 inspection when configured with the Snort 2 detection engine for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the CPU of an affected device to spike to 100 percent, which could stop all traffic processing and result in a denial of service (DoS) condition. FTD management traffic is not affected by this vulnerability. This vulnerability is due to improper error checking when parsing fields within the ICMPv6 header. An attacker could exploit this vulnerability by sending a crafted ICMPv6 packet through an affected device. A successful exploit could allow the attacker to cause the device to exhaust CPU resources and stop processing traffic, resulting in a DoS condition. Note: To recover from the DoS condition, the Snort 2 Detection Engine or the Cisco FTD device may need to be restarted.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

0.9% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2023-11-01 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-11 19:33 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.9% in the next 30 days (EPSS).
• Severity: 8.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-11-01 18:15 UTC

Last modified

2026-08-11 19:33 UTC

Exploit probability

0.9% · EPSS, next 30 days

Weakness

CWE-835

Record status

Modified

Affected

• Cisco Secure Firewall Threat Defense ≤ 6.2.3.18
• Cisco Secure Firewall Threat Defense ≤ 6.4.0.17
• Cisco Secure Firewall Threat Defense ≤ 6.6.7.1
• Cisco Secure Firewall Threat Defense ≤ 6.7.0.3
• Cisco Secure Firewall Threat Defense ≤ 7.0.5
• Cisco Secure Firewall Threat Defense ≤ 7.1.0.3
• Cisco Secure Firewall Threat Defense ≤ 7.2.3
• Cisco Secure Firewall Threat Defense ≤ 7.3.1.1

Attack profile CVSS 3.1 · 8.6

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

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