CVE-2026-119425

EUVD-2026-113805
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
5.4 MEDIUM
ADJACENT_NETWORK
LOW
NONE
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).
VendorProductVersionSource
opnsenseopnsense
26.1.6 ≤
𝑥
≤ 26.7.7
CNA
Common Weakness Enumeration
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
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