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Kaon AR2140X EUVDEUVD-2026-88247

| CVE-2026-52749 MEDIUM
Improper Authentication (CWE-287)
2026-09-28 CERT-PL GHSA-rmcq-5353-m59x
5.3
CVSS 4.0 · Vendor: CERT-PL
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Gain adjacent-network access to router
  2. Delivery
    Send unauthenticated HTTP request
  3. Exploit
    Receive valid session cookie without credentials
  4. Execution
    Invoke upgrade-related functionality with session
  5. Impact
    Force router to issue GET requests to arbitrary domains

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication mechanism validation
MITRE ATT&CK

2 techniques across 2 tactics: Defense Evasion, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires adjacent-network position (AV:A) - the attacker must reach the router's HTTP interface from the local LAN/Wi-Fi segment, not the public Internet. No credentials or user interaction are needed (PR:N/UI:N): the router itself issues a valid session cookie in response to an unauthenticated HTTP request, and that session grants access to upgrade-related functionality that can be coerced into issuing GET requests to arbitrary domains. Applies to firmware versions up to 4.2.17; status of newer firmware is unknown. Limiting factors: local-network adjacency requirement, limited (Low) confidentiality/integrity impact, no availability impact, and the narrow deployment base of this specific CPE model.

Impact

The vendor CVSS 4.0 base score is 5.3 (medium), and the vector is the key limiter: AV:A means the attacker must be on the adjacent/local network (LAN or Wi-Fi segment), not the open Internet - this is NOT a remotely-Internet-exploitable flaw despite being unauthenticated (PR:N/UI:N/AC:L). Impact is capped at VC:L/VI:L with a scope change to subsequent systems (SC:L/SI:L), consistent with the described outcome: an attacker obtains a valid session without credentials and abuses upgrade-related functionality to make the router issue GET requests to arbitrary domains (an SSRF/open-proxy-style primitive), rather than achieving full device compromise or code execution. No EPSS score, no CISA KEV listing, and no public POC were provided, so this maps to 'no public exploit identified at time of analysis.' Net: this is a legitimate authentication-bypass finding but a realistically LOW real-world priority - the adjacent-network requirement, limited (Low) impact, absence of exploitation signals, and the narrow/obscure device footprint all pull against urgency. One data caveat: the sole reference URL points to CVE-2026-52748 while this record is CVE-2026-52749, and the CPE lists 'ar2140' whereas the description names the 'AR2140X' - verify the exact product/reference mapping with CERT-PL.

Exploit ScenarioDerived

An attacker on the same local network as the router (e.g., a guest Wi-Fi client or a compromised LAN host) sends an unauthenticated HTTP request and is issued a valid session cookie without any credentials. Using that session, the attacker invokes upgrade-related functionality to coerce the router into issuing attacker-controlled GET requests to arbitrary domains, effectively turning the device into a request proxy. No public exploit code was identified at the time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 28, 2026

Authentication bypass in Kaon AR2140X routers (firmware versions up to 4.2.17) allows unauthenticated attackers on the adjacent network to obtain a valid session cookie and access upgrade-related functionality, which can be abused to force the device to issue GET requests to arbitrary domains. The flaw requires local LAN or Wi-Fi adjacency (AV:A) and carries low confidentiality/integrity impact with no availability impact; no public exploit has been identified, and the status of firmware newer than 4.2.17 remains unknown.

RemediationAI

No vendor-released patch was identified at time of analysis; users should contact Kaon for updated firmware beyond 4.2.17 and apply it if available. As compensating controls, restrict access to the router's HTTP management interface to trusted administrative hosts by using firewall rules or VLAN segmentation, and ensure untrusted network segments such as guest Wi-Fi cannot reach the admin interface. Disable remote management if it is not required, and monitor the router for unexpected outbound GET requests to arbitrary domains, which could indicate exploitation. These mitigations may reduce management flexibility or convenience, and if no firmware fix is forthcoming, replacing the device should be considered. The CERT-PL advisory at https://cert.pl/en/posts/2026/09/CVE-2026-52748 may provide further guidance.

Affected VersionsENISA

AR2140 0 ≤4.2.17

Affected Packages

euvd ar2140 no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability is classified as CWE-287 (Improper Authentication), meaning the router fails to verify that a requester has authenticated before issuing a session identifier. In practice, unauthenticated HTTP requests to the router's management interface receive a valid session cookie, which then grants access to upgrade-related functions without any credential check. This session can be leveraged to coerce the router into performing GET requests to attacker-chosen domains, potentially enabling server-side request forgery (SSRF) or forcing the device to interact with internal or external services. The CPE entry cpe:2.3:a:kaon:ar2140:*:*:*:*:*:*:*:* confirms that all versions of the Kaon AR2140 are in scope. The vendor CVSS 4.0 base score is 5.3 (medium), and the assessed CVSS 3.1 vector AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N underscores that the attack is unauthenticated and requires no user interaction but is limited to adjacent-network position; the scope-changed (S:C) element reflects that forced requests could affect resources beyond the router itself, though impact remains low.

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Severity by source

Vendor (CERT-PL) PRIMARY 5.3 MEDIUM
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
vuln.today AI 6.1 MEDIUM

Adjacent HTTP access (AV:A) with no auth/interaction (PR:N/UI:N); scope change (S:C) because the router is coerced to send GET requests to other systems, with limited C/I impact.

3.1 AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Primary rating from Vendor (CERT-PL).

CVSS VectorVendor: CERT-PL

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
Low
Subsequent system: Integrity
Low
Subsequent system: Availability
None

DescriptionCVE.org

The Kaon AR2140X router improperly issues session cookies in responses to unauthenticated HTTP requests. This vulnerability allows a remote attacker to obtain a valid session identifier without providing credentials, resulting in an authentication bypass. With this access, the attacker can perform unauthorized actions on upgrade-related functionalities. These actions can be abused to force the router to issue GET requests to arbitrarily chosen domains.

This issue was identified in firmware versions up to 4.2.17. Status of newer versions remains unknown.

Threat Intelligence Overview

EPSS Score
0.3%
Top 84% exploitable
Prevalence
Low
Niche ISP-supplied Kaon CPE router, limited regional footprint
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Controlled
Automatable
Yes
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

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