---
id: CVE-2018-0138
title: >-
  A vulnerability in the detection engine of Cisco Firepower System Software
  could allow an unauthenticated, remote attacker to bypass file policies that
  are configured to block files transmitted to an affected device via the
  BitTorrent pr…
summary: >-
  A vulnerability in the detection engine of Cisco Firepower System Software
  could allow an unauthenticated, remote attacker to bypass file policies that
  are configured to block files transmitted to an affected device via the
  BitTorrent pr…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-693
  - CWE-693
vendor: cisco
product: secure_firewall_threat_defense
affected:
  - secure_firewall_threat_defense = 6.1.0
  - secure_firewall_threat_defense = 6.2.0
  - secure_firewall_threat_defense = 6.2.2
  - secure_firewall_threat_defense = 6.2.3
published: '2018-02-08'
updated: '2026-08-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2018-0138'
references:
  - url: 'http://www.securityfocus.com/bid/102978'
    label: psirt@cisco.com
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180207-fss
    label: psirt@cisco.com
  - url: 'http://www.securityfocus.com/bid/102978'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180207-fss
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.01163
epssPercentile: 0.6585
ingestedAt: '2026-08-11T19:48:25.437Z'
---

## Overview

A vulnerability in the detection engine of Cisco Firepower System Software could allow an unauthenticated, remote attacker to bypass file policies that are configured to block files transmitted to an affected device via the BitTorrent protocol. The vulnerability exists because the affected software does not detect BitTorrent handshake messages correctly. An attacker could exploit this vulnerability by sending a crafted BitTorrent connection request to an affected device. A successful exploit could allow the attacker to bypass file policies that are configured to block files transmitted to the affected device via the BitTorrent protocol. Cisco Bug IDs: CSCve26946.

## Affected

- `secure_firewall_threat_defense = 6.1.0`
- `secure_firewall_threat_defense = 6.2.0`
- `secure_firewall_threat_defense = 6.2.2`
- `secure_firewall_threat_defense = 6.2.3`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.