---
id: CVE-2018-0254
title: >-
  A vulnerability in the detection engine of Cisco Firepower System Software
  could allow an unauthenticated, remote attacker to bypass configured file
  action policies if an Intelligent Application Bypass (IAB) with a drop
  percentage thresh…
summary: >-
  A vulnerability in the detection engine of Cisco Firepower System Software
  could allow an unauthenticated, remote attacker to bypass configured file
  action policies if an Intelligent Application Bypass (IAB) with a drop
  percentage thresh…
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 = 6.1.0.5
  - secure_firewall_threat_defense = 6.2.0.2
  - secure_firewall_threat_defense = 6.2.1
  - secure_firewall_threat_defense = 6.2.2
published: '2018-04-19'
updated: '2026-08-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2018-0254'
references:
  - url: 'http://www.securityfocus.com/bid/103940'
    label: psirt@cisco.com
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-fss2
    label: psirt@cisco.com
  - url: 'http://www.securityfocus.com/bid/103940'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-fss2
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.01365
epssPercentile: 0.70167
ingestedAt: '2026-08-11T19:48:25.708Z'
---

## Overview

A vulnerability in the detection engine of Cisco Firepower System Software could allow an unauthenticated, remote attacker to bypass configured file action policies if an Intelligent Application Bypass (IAB) with a drop percentage threshold is also configured. The vulnerability is due to incorrect counting of the percentage of dropped traffic. An attacker could exploit this vulnerability by sending network traffic to a targeted device. An exploit could allow the attacker to bypass configured file action policies, and traffic that should be dropped could be allowed into the network. Cisco Bug IDs: CSCvf86435.

## Affected

- `secure_firewall_threat_defense = 6.1.0.5`
- `secure_firewall_threat_defense = 6.2.0.2`
- `secure_firewall_threat_defense = 6.2.1`
- `secure_firewall_threat_defense = 6.2.2`

## Remediation

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