CVE-2017-6766

What it is

A vulnerability in the Secure Sockets Layer (SSL) Decryption and Inspection feature of Cisco Firepower System Software 5.4.0, 5.4.1, 6.0.0, 6.1.0, 6.2.0, 6.2.1, and 6.2.2 could allow an unauthenticated, remote attacker to bypass the SSL policy for decrypting and inspecting traffic on an affected system. The vulnerability is due to unexpected interaction with Known Key and Decrypt and Resign configuration settings of SSL policies when the affected software receives unexpected SSL packet headers. An attacker could exploit this vulnerability by sending a crafted SSL packet through an affected device in a valid SSL session. A successful exploit could allow the attacker to bypass the SSL decryption and inspection policy for the affected system, which could allow traffic to flow through the system without being inspected. Cisco Bug IDs: CSCve12652.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data tampering.

Exploit odds

1.3% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2017-08-07 06:29 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 01:23 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.3% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2017-08-07 06:29 UTC

Last modified

2026-06-17 01:23 UTC

Exploit probability

1.3% · EPSS, next 30 days

Weakness

CWE-310

Record status

Modified

Affected

• Cisco Firesight System Software 5.4.0
• Cisco Firesight System Software 5.4.1
• Cisco Firesight System Software 6.0.0
• Cisco Firesight System Software 6.1.0
• Cisco Firesight System Software 6.2.0
• Cisco Firesight System Software 6.2.1
• Cisco Firesight System Software 6.2.2

Attack profile CVSS 3.0 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2017-6766.md and follow it. Check whether this project is affected by CVE-2017-6766. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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