---
id: CVE-2026-119425
title: OPNsense 26.1.6 through 26.7.7 Captive Portal Session Takeover via Forged ARP
summary: >-
  OPNsense core 26.1.6 through 26.7.7 contains an authentication bypass
  vulnerability in the captive portal roaming feature that lets unauthenticated
  attackers hijack authorized client sessions by spoofing unauthenticated
  MAC-to-IP observa…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-290
vendor: opnsense
product: core
affected:
  - core >= 26.1.6 <= 26.7.7
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-30T15:20:58.656589Z'
published: '2026-10-30'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T15:55:05.938Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-119425'
references:
  - url: 'https://github.com/opnsense/core/security/advisories/GHSA-864r-q4j5-5mjq'
    label: GitHub Security Advisory (GHSA-864r-q4j5-5mjq)
  - url: >-
      https://github.com/opnsense/core/commit/f46836d0c3d14e26d79214009bfbfa9a1eecab55
    label: Incomplete fix
  - url: >-
      https://github.com/opnsense/core/commit/32dc2a3e52eefef5251077f315a0f3243eedb834
    label: Incomplete fix (stable/26.7)
  - url: >-
      https://github.com/opnsense/core/blob/26.7.7/src/opnsense/scripts/captiveportal/cp-background-process.py#L78
  - url: 'https://abraxaslabs.tech/research/opnsense-captive-lastseen-roam'
  - url: 'https://github.com/opnsense/core'
  - url: >-
      https://www.vulncheck.com/advisories/opnsense-26.1.6-through-26.7.7-captive-portal-session-takeover-via-forged-arp
    label: >-
      VulnCheck Advisory: OPNsense 26.1.6 through 26.7.7 Captive Portal Session
      Takeover via Forged ARP
tags:
  - cve.org
epss: 0.00313
epssPercentile: 0.24369
ingestedAt: '2026-11-05T16:07:30.523Z'
---

## Overview

OPNsense core 26.1.6 through 26.7.7 contains an authentication bypass vulnerability in the captive portal roaming feature that lets unauthenticated attackers hijack authorized client sessions by spoofing unauthenticated MAC-to-IP observations. Attackers on the same Layer-2 segment can send forged gratuitous ARP replies binding their IP to a victim's MAC, gaining portal access with traffic attributed to the victim.

## Affected

- `core >= 26.1.6 <= 26.7.7`

## Remediation

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