CVE-2026-66747

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National Vulnerability Database Information

Description: Zbtlink router firmware ships an embedded remote-control implant, ENDLESSDOORS, present in every published build across the product line. It is the open-source ycsunjane/rctl tool built in as an OpenWrt package (librctl.so), started at boot and run as root under the process name kworker to blend in with the kernel's [kworker/*] threads. It opens no listening port; it phones home over cleartext TCP to a hardcoded command-and-control server (command channel 7000, interactive-shell callback 7001) with no authentication and no transport encryption, re-attempting contact roughly every 35 seconds. Its command handler passes any received string to popen() as uid=0, and a reserved rctlbash command returns an interactive root shell. Because the channel is unauthenticated and cleartext, control is not limited to whoever planted it: any party that answers at the C2 address, occupies the network path (DNS or route hijack), or acquires the hardcoded fallback domain obtains unauthenticated remote code execution as root.

CVSS Base Score: 9.8 (v3.1)

The CVSS Base Score is a score from 0 to 10 that represents the intrinsic severity of a vulnerability. A higher score indicates greater severity.

Value

0.02.55.07.510.0

Published on: 08/05/2026 11:16:25
Last modified: 08/05/2026 15:17:04
NIST: CVE source from the National Vulnerability Database (NVD)

CVSS Metrics Details

Base Severity: CRITICAL
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector: NETWORK
Attack Complexity: LOW
Privileges Required: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality Impact: HIGH
Integrity Impact: HIGH
Availability Impact: HIGH

Common Weakness Enumeration (CWE)

Database CWE: v4.18

CWE-506: Embedded Malicious Code ↗

The product contains code that appears to be malicious in nature.

Fonte: MITRE CWE

FIRST Information

EPSS Score: 0.0062

The EPSS (Exploit Prediction Scoring System) is a score from 0 to 1 that indicates the probability that a vulnerability will be exploited in the real world in the next 30 days. A higher value indicates a greater likelihood of exploitation.

Value

0.00.250.50.751.0

Percentile: 0.4689

The Percentile indicates how much higher this vulnerability's EPSS score is compared to all other vulnerabilities in the EPSS database. For example, a percentile of 0.90 (90%) means that 90% of vulnerabilities have an EPSS score equal to or lower than the current one.

Value

0.00.250.50.751.0

*Data updated as of: 2026-08-25

CISA Information (Known Exploited Vulnerabilities)

The CISA KEV Catalog lists vulnerabilities that have been actively exploited in the real world. If a CVE is present in this catalog, it indicates that the threat is immediate and mitigation should be a top priority.

CVE CVE-2026-66747 is not present in the CISA KEV Catalog. This indicates that it is not currently classified by CISA as an actively exploited vulnerability.

Articles published on Red Hot Cyber

No articles present on Red Hot Cyber.

NVD References

Exploit PoC from GitHub

oiehnow/oieh-router-checker: 내 공유기가 Zbtlink ENDLESSDOORS 백도어(CVE-2026-66747) 대상인지 클릭 한 번으로 검사하는 Windows 프로그램