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KAON PG5298 CVE-2026-6017

| EUVDEUVD-2026-64827 HIGH
Missing Authentication for Critical Function (CWE-306)
2026-08-24 CERT-PL GHSA-4v96-chmw-8jc6
7.1
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
  2. Delivery
    Send unauthenticated HTTP request to firmware endpoint
  3. Exploit
    Receive admin portal credentials in response
  4. Execution
    Authenticate to administrative interface
  5. Impact
    Achieve full router control

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication required for critical functions
MITRE ATT&CK

1 technique across 1 tactic: Initial Access

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

Exploitation Conditions

Exploitation requires the attacker to be on the same adjacent network segment as the vulnerable router - such as the same LAN, Wi-Fi SSID, or ISP-shared local segment - consistent with the CVSS 4.0 AV:A metric. Once adjacency is established, no credentials, user interaction, special configuration, or privilege escalation are required; the attack is a single unauthenticated request to a specific endpoint. Exploitation is limited by: (1) the adjacency requirement - remote internet attackers cannot exploit this without first gaining local network access via another vector; (2) the device must be running firmware prior to 3.0.82 (PG5298A) or 4.0.82 (PG5298B). The specific vulnerable endpoint URL is not publicly disclosed in available intelligence. There is no indication that the WAN interface exposes the vulnerable endpoint, and the CVSS 4.0 vector confirms no attack prerequisites beyond adjacency.

Impact

The CVSS 4.0 score of 7.1 with AV:A is the defining constraint on real-world risk: exploitation requires the attacker to already be on the same network segment as the router - the same LAN, Wi-Fi network, or equivalent adjacency. This rules out mass internet-based exploitation and substantially reduces the attacker population compared to AV:N vulnerabilities. Within that constraint, however, exploitation is maximally easy: AC:L, AT:N, PR:N, and UI:N mean no complexity, no preconditions, no credentials, and no victim interaction are required. The confidentiality impact is high (VC:H) because the disclosed credential grants full administrative access to the device. No EPSS data was provided in the available intelligence, and the vulnerability is not listed in CISA KEV, indicating no confirmed active exploitation. For ISP-deployed residential or SMB routers, realistic threat actors include co-tenants in shared apartment buildings, users on shared Wi-Fi, or attackers who have already achieved LAN-level access via another vector. The adjacent-vector constraint makes automated internet-scale scanning infeasible, but the trivial exploitation mechanics and high-value credential output make targeted local-network attacks a meaningful risk.

Exploit ScenarioDerived

An attacker connected to the same Wi-Fi network as a vulnerable KAON router - such as a neighbor exploiting a shared ISP access segment, or a guest user - sends a simple unauthenticated HTTP request to the undisclosed firmware endpoint. The router responds with the administrative portal password, which the attacker then uses to log into the management interface and gain full device control, enabling persistent DNS manipulation, traffic interception, or firmware replacement. No public exploit code is known, but the low complexity of the attack (single unauthenticated HTTP request) makes independent development trivial for any attacker with local network access.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 24, 2026

Unauthenticated information disclosure in KAON PG5298A and PG5298B router firmware exposes the administrative portal password to any attacker on the same local network segment. An adjacent-network attacker can query a specific firmware endpoint without credentials and retrieve sensitive authentication material, enabling full device takeover. Vendor-released patches are available in firmware versions 3.0.82 (PG5298A) and 4.0.82 (PG5298B); no public exploit code or confirmed active exploitation has been identified at time of analysis.

RemediationAI

The primary remediation is a firmware upgrade: PG5298A devices should be updated to firmware version 3.0.82 or later, and PG5298B devices to firmware version 4.0.82 or later. Firmware updates are typically applied through the device's administrative web interface or pushed by the ISP. The CERT-PL advisory at https://cert.pl/en/posts/2026/08/CVE-2025-63080/ provides further guidance. Where immediate patching is not possible, compensating controls should focus on reducing the attack surface of the adjacent network: isolate untrusted devices (guests, IoT) onto a separate VLAN or SSID so they cannot reach the router's LAN management interface; disable Wi-Fi access for untrusted users; and confirm the vulnerable endpoint is not reachable from the WAN interface. These measures narrow the attacker population but do not eliminate the vulnerability - patch deployment remains the only definitive fix.

Affected VersionsENISA

PG5298B 0 <4.0.82
PG5298A 0 <3.0.82

Affected Packages

euvd pg5298a fix: 3.0.82
euvd pg5298b fix: 4.0.82

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

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

Technical ContextAI · show details

CWE-306 (Missing Authentication for Critical Function) describes the root cause: the router firmware exposes an HTTP or API endpoint that returns sensitive credential data - specifically the admin portal password - without enforcing any access control check. The affected products, identified by CPE cpe:2.3:a:kaon:pg5298a:*:*:*:*:*:*:*:* and cpe:2.3:a:kaon:pg5298b:*:*:*:*:*:*:*:*, are broadband gateway routers manufactured by KAON, a vendor that primarily supplies CPE hardware to ISPs. The CVSS 4.0 adjacent-network vector (AV:A) indicates the vulnerable endpoint is accessible over the LAN or local wireless interface rather than the WAN/internet-facing interface, consistent with firmware management APIs that are typically scoped to the internal network but lack proper authentication gates.

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Severity by source

Vendor (CERT-PL) PRIMARY 7.1 HIGH
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
vuln.today AI 6.5 MEDIUM

Adjacent-only reachability enforced by AV:A; unauthenticated endpoint (PR:N) discloses credentials with no integrity or availability impact.

3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/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
High
Vulnerable system: Integrity
None
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

2
Patch available
Aug 24, 2026 - 12:01 EUVD
CVE Published
Aug 24, 2026 - 11:11 cve.org
HIGH 7.1

DescriptionCVE.org

Firmware in KAON PG5298A and PG5298B routers allow an unauthenticated user to query a specific endpoint and acquire sensitive information such as a password to the administrative portal. This vulnerability has been fixed in firmware version: 3.0.82 for PG5298A and 4.0.82 for PG5298B.

Executive ViewAI

Why It Matters

KAON PG5298A and PG5298B routers contain an unauthenticated information disclosure flaw that exposes administrative credentials to any attacker on the same network segment, enabling full device compromise. Organizations using these routers face immediate risk of unauthorized administrative access and network infiltration. Prompt firmware patching is required to eliminate credential exposure.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.2%
Top 95% exploitable
Prevalence
Low
niche ISP-distributed broadband router with limited global market footprint
Data Quality
5 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 HIGH
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Controlled
Automatable
No
Human Impact
High
Technical Impact
Partial

Priority Score

36
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +36
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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