VulnerabilityPublished 30 Oct 2026

CVE-2026-119425: opnsense core · Authentication Bypass by Spoofing

Affects opnsense coreSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium.

Data as of 30 Oct 2026, 12:04 UTC

CVSS 4.0 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (VulnCheck)	CVSS 4.0	5.3
CNA (VulnCheck)	CVSS 3.1	5.4

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

Attack Vector: Adjacent
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Adjacent: The vulnerable system is bound to a protocol stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared proximity (e.g., Bluetooth, NFC, or IEEE 802.11) or logical network (e.g., local IP subnet), or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN within an administrative network zone).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 30 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
opnsensecore	Affected >=26.1.6 <=26.7.7	Fixed in–
GitHubcore`pkg:github/core`Other threats	Affected >=26.1.6 <=26.7.7	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is available, network administrators should consider mitigating this risk by restricting Layer-2 network access, implementing ARP spoofing detection/prevention mechanisms, or isolating captive portal clients to prevent ARP spoofing attacks.

Description

OPNsense core versions 26.1.6 through 26.7.7 have an authentication bypass vulnerability in the captive portal roaming feature. This flaw allows unauthenticated attackers on the same Layer-2 network segment to hijack authorized client sessions by spoofing MAC-to-IP bindings via forged gratuitous ARP replies. Exploitation results in portal access with traffic attributed to the victim.

Impact

An attacker on the same Layer-2 segment can bypass captive portal authentication controls by spoofing MAC-to-IP bindings, allowing unauthorized access to the network with the victim's session identity. This can lead to unauthorized network access and potential misuse of the victim's session privileges. The CVSS 4.0 base score is 5.3 (medium severity), reflecting the network attack vector with low complexity and no required privileges or user interaction.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 11:51 UTC

Technical details

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