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Vulnerabilities & CVEs BleepingComputer 1 month ago

Unpatched Calix flaw lets hackers bypass NAT to expose internal devices

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CyberNew Threat Research Desk
• Original Reporting: BleepingComputer
CyberNew Threat Intel Assessment
Assessed Severity: CRITICAL
Impacted Surface
Enterprise Perimeter & Network Defense
Intelligence Sector
Vulnerabilities & CVEs

Analyst Takeaway

"An unpatched vulnerability in Calix GS7 XGS (GS5239XG) residential routers used by multiple U.S. broadband providers allows remote, unauthenticated attackers to create port-forwarding rules that can expose local network devices to the public internet. The flaw is tracked as CVE-2026-75501 and is described as a missing authentication issue that affects devices running EXOS/6.6.47 firmware...."

Recommended Defense & Mitigation

  • Emergency Patching: Prioritize vendor patches and CVE mitigation across internet-facing assets immediately.
  • Perimeter Audit: Inspect perimeter firewall logs and hunt for unauthorized RCE indicators.
Curated & Verified by CyberNew Threat Intelligence Desk Standard Defense Framework (NIST / MITRE ATT&CK)

Unpatched Calix flaw lets hackers bypass NAT to expose internal devices

An unpatched vulnerability in Calix GS7 XGS (GS5239XG) residential routers used by multiple U.S. broadband providers allows remote, unauthenticated attackers to create port-forwarding rules that can expose local network devices to the public internet.

The flaw is tracked as CVE-2026-75501 and is described as a missing authentication issue that affects devices running EXOS/6.6.47 firmware.

Security researcher Brian Khan Quintana discovered the flaw and, after trying to notify the vendor on June 7 without success, he reported the vulnerability to the Carnegie Mellon CERT Coordination Center.

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Following multiple attempts to contact the vendor and receiving no response, CERT/CC coordinated a public disclosure, and Quintana published the technical details.

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Source Verification & Original Intelligence

This threat report was reviewed by CyberNew analysts and cross-referenced with primary security disclosures from BleepingComputer.

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