CVE-2026-73673

Netis NC63 router firmware V3.0.0.3327 contains an unauthenticated firmware update vulnerability that allows unauthenticated attackers to submit unsigned firmware images by exploiting a missing authentication enforcement flaw in the Boa web server and netis.cgi CGI dispatcher. Attackers can send a multipart POST request to /cgi-bin/upload_fw.cgi without a valid session cookie, bypassing authentication because Boa grants access to any path containing '.cgi' regardless of cookie validation, and netis.cgi reads but does not enforce the authentication state before invoking the firmware update handler, which accepts images validated only by a forgeable additive checksum and static product strings rather than a cryptographic signature, potentially enabling persistent router compromise.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector ADJACENT_NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/ozcanpng/CVE-2026-73673
https://ozcanpng.dev/blog/cve-2026-73673-netis-nc63-unauthenticated-firmware-update/
https://www.netis-systems.com/products/NC63.html
https://www.netis-systems.com/support/downinfo.html?id=35
https://www.vulncheck.com/advisories/netis-nc63-unauthenticated-firmware-update-with-missing-cryptographic-firmware-authentication

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-14 13:19

Updated : 2026-08-14 16:17

NVD link : CVE-2026-73673

Mitre link : CVE-2026-73673

CVE.ORG link : CVE-2026-73673

JSON object : View

Products Affected

No product.

CWE

CWE-306

Missing Authentication for Critical Function

{"id": "CVE-2026-73673", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-73673", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-08-14T14:40:50.687314Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8.8, "attackVector": "ADJACENT_NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 2.8}], "cvssMetricV40": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 8.7, "Automatable": "NOT_DEFINED", "attackVector": "ADJACENT", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "disclosure@vulncheck.com", "affectedData": [{"vendor": "Netis Systems Co., Ltd.", "product": "Netis NC63 Wireless AC1200 Router", "versions": [{"status": "affected", "version": "0", "versionType": "custom", "lessThanOrEqual": "V3.0.0.3327"}], "packageURL": "pkg:cargo/dua-cli", "defaultStatus": "affected"}]}], "published": "2026-08-14T13:19:09.573", "references": [{"url": "https://github.com/ozcanpng/CVE-2026-73673", "source": "disclosure@vulncheck.com"}, {"url": "https://ozcanpng.dev/blog/cve-2026-73673-netis-nc63-unauthenticated-firmware-update/", "source": "disclosure@vulncheck.com"}, {"url": "https://www.netis-systems.com/products/NC63.html", "source": "disclosure@vulncheck.com"}, {"url": "https://www.netis-systems.com/support/downinfo.html?id=35", "source": "disclosure@vulncheck.com"}, {"url": "https://www.vulncheck.com/advisories/netis-nc63-unauthenticated-firmware-update-with-missing-cryptographic-firmware-authentication", "source": "disclosure@vulncheck.com"}], "vulnStatus": "Received", "weaknesses": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "description": [{"lang": "en", "value": "CWE-306"}]}], "descriptions": [{"lang": "en", "value": "Netis NC63 router firmware V3.0.0.3327 contains an unauthenticated firmware update vulnerability that allows unauthenticated attackers to submit unsigned firmware images by exploiting a missing authentication enforcement flaw in the Boa web server and netis.cgi CGI dispatcher. Attackers can send a multipart POST request to /cgi-bin/upload_fw.cgi without a valid session cookie, bypassing authentication because Boa grants access to any path containing '.cgi' regardless of cookie validation, and netis.cgi reads but does not enforce the authentication state before invoking the firmware update handler, which accepts images validated only by a forgeable additive checksum and static product strings rather than a cryptographic signature, potentially enabling persistent router compromise."}], "lastModified": "2026-08-14T16:17:00.530", "sourceIdentifier": "disclosure@vulncheck.com"}