# CVE-2017-6766: Security feature bypass in Cisco Firepower System Software

> An unauthenticated remote attacker can bypass SSL decryption and inspection policies by sending crafted SSL packets, allowing malicious traffic to pass uninspected.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Aug 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-q3pq-v78p-xj7q

## What is CVE-2017-6766?

CVE-2017-6766 is a high-severity vulnerability in Cisco Firepower System Software, published on 7 Aug 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-310

## Which versions are affected by CVE-2017-6766?

It affects 1 product.


Products: Cisco Firesight System Software.

## How do I fix CVE-2017-6766?

No fix has been published for CVE-2017-6766 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-6766 being exploited?

There is no known exploitation of CVE-2017-6766 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Firepower System Software

- [CVE-2016-6394](https://insights.sbomify.com/CVE-2016-6394/): Auth bypass in n/a (critical 9.1)
- [CVE-2015-6335](https://insights.sbomify.com/CVE-2015-6335/): Privilege escalation in n/a (critical 9.0)
- [CVE-2016-6417](https://insights.sbomify.com/CVE-2016-6417/): Cross-site request forgery in n/a (high 8.8)
- [CVE-2016-1394](https://insights.sbomify.com/CVE-2016-1394/): Hardcoded credentials in n/a (high 8.6)
- [CVE-2016-9193](https://insights.sbomify.com/CVE-2016-9193/): Security feature bypass in Cisco FireSIGHT (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-6766 and fix it if it is affected.

What it is: CVE-2017-6766 is a high-severity vulnerability in Cisco Firepower System Software, published on 7 Aug 2017. 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-2017-6766 in the wild and no public exploit code.

Affected product: Cisco Firepower System Software. 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-2017-6766/ (Markdown: https://insights.sbomify.com/CVE-2017-6766/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-6766
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-6766
- OSV: https://osv.dev/vulnerability/CVE-2017-6766

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From sbomify Insights: https://insights.sbomify.com/CVE-2017-6766/
Summaries are generated and may contain mistakes; the official description above is the record.