# CVE-2021-34749: Multiple Cisco Products Server Name Identification Data Exfiltration Vulnerability

> Unauthenticated attackers can bypass SSL filtering to exfiltrate data from compromised hosts via SNI requests in Cisco WSA, FTD, and Snort.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Aug 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-x64m-mg53-f49j, UBUNTU-CVE-2021-34749

## What is CVE-2021-34749?

CVE-2021-34749 is a medium-severity vulnerability in Cisco Secure Firewall Management Center, published on 18 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in Server Name Identification (SNI) request filtering of Cisco Web Security Appliance (WSA), Cisco Firepower Threat Defense (FTD), and the Snort detection engine could allow an unauthenticated, remote attacker to bypass filtering technology on an affected device and exfiltrate data from a compromised host. This vulnerability is due to inadequate filtering of the SSL handshake. An attacker could exploit this vulnerability by using data from the SSL client hello packet to communicate with an external server. A successful exploit could allow the attacker to execute a command-and-control attack on a compromised host and perform additional data exfiltration attacks.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2021-34749?

It affects 3 products.


Products: Cisco Firepower Management Center Virtual Appliance Firmware, Cisco Ironport Web Security Appliance, Cisco Secure Firewall Management Center.

## How do I fix CVE-2021-34749?

Apply the vendor's patch.

## Is CVE-2021-34749 being exploited?

There is no known exploitation of CVE-2021-34749 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34749 and fix it if it is affected.

What it is: CVE-2021-34749 is a medium-severity vulnerability in Cisco Secure Firewall Management Center, published on 18 Aug 2021. 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-2021-34749 in the wild and no public exploit code.

Affected product: Cisco Secure Firewall Management Center. 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-2021-34749/ (Markdown: https://insights.sbomify.com/CVE-2021-34749/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34749
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34749
- OSV: https://osv.dev/vulnerability/CVE-2021-34749

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34749/
Summaries are generated and may contain mistakes; the official description above is the record.