CVE-2025-62843Known exploitation

Unauthenticated firewall bypass via IPv6 PPPoE mismatch

Published Mar 20, 2026 · Updated Mar 20, 2026

Firewall bypass in QNAP QuRouter 2.6.x before 2.6.3.009 allows network-adjacent attackers to evade IPv6 rules on QHora-322 routers. The ip6_wanifset firewall implementation fails to match IPv6 firewall rules on PPPoE connections, allowing prohibited traffic to pass. No authentication is required, and successful bypass can be chained with other flaws to execute arbitrary code as root.

CVSS severity6.8
Medium
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Firewall bypass in QNAP QuRouter 2.6.x before 2.6.3.009 allows network-adjacent attackers to evade IPv6 rules on QHora-322 routers. The ip6_wanifset firewall implementation fails to match IPv6 firewall rules on PPPoE connections, allowing prohibited traffic to pass. No authentication is required, and successful bypass can be chained with other flaws to execute arbitrary code as root.

The record

CVE
CVE-2025-62843
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
Linn Products Limited
Product
QuRouter
Classifications
CWE-923
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.x <2.6.3.009

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Linn Products Limited · QuRouterversion=2.6.x <2.6.3.009

Published CVSS scores

6.8NIST NVDCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
0.9QNAP Systems, Inc.CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:U
6.3Trend Micro Zero Day InitiativeCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-923Improper Restriction of Communication Channel to Intended Endpoints

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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