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Vulnerability record · CVE-2021-35327 · published 5 August 2021

CVE-2021-35327: Totolink a720r firmware missing authorization vulnerability

TTotolink · A720r Firmware

A vulnerability in TOTOLINK A720R A720R_Firmware v4.1.5cu.470_B20200911 allows attackers to start the Telnet service, then login with the default credentials via a crafted POST request.

9.8 CVSS 3.1 Critical EPSS 1.4% · top 28.9% CWE-862 · Missing authorization
9.8CVSS 3.1 base score, v2 7.5
1.4%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

A vulnerability in TOTOLINK A720R A720R_Firmware v4.1.5cu.470_B20200911 allows attackers to start the Telnet service, then login with the default credentials via a crafted POST request.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/hurricane618/my_cves/blob/master/router/totolink/A720R_default_telnet_info.md ExploitThird Party Advisory
https://github.com/hurricane618/my_cves/blob/master/router/totolink/A720R_default_telnet_info.md ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2023-23064Totolink a720r firmware incorrect authorization vulnerabilityTOTOLINK A720R V4.1.5cu.532_ B20210610 is vulnerable to Incorrect Access Control.EPSS 0.70%9.8CVE-2021-45740Totolink a720r firmware vulnerabilityTOTOLINK A720R v4.1.5cu.470_B20200911 was discovered to contain a stack overflow in the setWiFiWpsStart function. This vulnerability allows attackers…EPSS 1.4%9.8CVE-2021-45742Totolink a720r firmware command injection vulnerabilityTOTOLINK A720R v4.1.5cu.470_B20200911 was discovered to contain a command injection vulnerability in the "Main" function. This vulnerability allows a…EPSS 3.1%9.8CVE-2021-44247Totolink a720r firmware command injection vulnerabilityTotolink devices A3100R v4.1.2cu.5050_B20200504, A830R v5.9c.4729_B20191112, and A720R v4.1.5cu.470_B20200911 were discovered to contain command inje…EPSS 2.8%9.8CVE-2021-35324Totolink a720r firmware vulnerabilityA vulnerability in the Form_Login function of TOTOLINK A720R A720R_Firmware V4.1.5cu.470_B20200911 allows attackers to bypass authentication.EPSS 10%9.8CVE-2021-27710Totolink x5000r firmware os command injection vulnerabilityCommand Injection in TOTOLINK X5000R router with firmware v9.1.0u.6118_B20201102, and TOTOLINK A720R router with firmware v4.1.5cu.470_B20200911 allo…EPSS 7.9%9.8CVE-2021-27708Totolink x5000r firmware os command injection vulnerabilityCommand Injection in TOTOLINK X5000R router with firmware v9.1.0u.6118_B20201102, and TOTOLINK A720R router with firmware v4.1.5cu.470_B20200911 allo…EPSS 7.6%7.8CVE-2022-36610Totolink a720r firmware hard-coded credentials vulnerabilityTOTOLINK A720R V4.1.5cu.532_B20210610 was discovered to contain a hardcoded password for root at /etc/shadow.sample.EPSS 0.30%

Source: NIST National Vulnerability Database (record CVE-2021-35327), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.