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://abraxaslabs.tech/research/opnsense-captive-lastseen-roam
• https://github.com/opnsense/core
• https://github.com/opnsense/core/blob/26.7.7/src/opnsense/scripts/captiveportal/cp-background-process.py#L78
• https://github.com/opnsense/core/commit/32dc2a3e52eefef5251077f315a0f3243eedb834
• https://github.com/opnsense/core/commit/f46836d0c3d14e26d79214009bfbfa9a1eecab55