CVE-2026-119425

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.

References

https://www.vulncheck.com/advisories/opnsense-26.1.6-through-26.7.7-captive-portal-session-takeover-via-forged-arp

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://github.com/opnsense/core

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-113805

https://abraxaslabs.tech/research/opnsense-captive-lastseen-roam

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS