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.

Metrics

CVSS 3.1

5.4 (MEDIUM) Score source: CNA CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS 4.0

5.3 (MEDIUM) Score source: CNA 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — exploit probability

0% (percentile: 24) as of 1 November 2026

CWE

CWE-290

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…
• 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-por…