CVE-2026-119425

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.

• 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
• https://github.com/opnsense/core/security/advisories/GHSA-864r-q4j5-5mjq

• 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
• https://github.com/opnsense/core/security/advisories/GHSA-864r-q4j5-5mjq
• https://www.vulncheck.com/advisories/opnsense-26.1.6-through-26.7.7-captive-portal-session-takeover-via-forged-arp

• CRITICALCVE-2022-51026PoC
• MEDIUMCVE-2023-54411PoC
• UNSCOREDCVE-2025-30052
• HIGHCVE-2026-100390PoC
• HIGHCVE-2026-101280
• HIGHCVE-2026-102161
• CRITICALCVE-2026-102764
• CRITICALCVE-2026-102946PoC

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