CVE-2021-34203

D-Link DIR-2640-US 1.01B04 is vulnerable to Incorrect Access Control. Router ac2600 (dir-2640-us), when setting PPPoE, will start quagga process in the way of whole network monitoring, and this function uses the original default password and port. An attacker can easily use telnet to log in, modify routing information, monitor the traffic of all devices under the router, hijack DNS and phishing attacks. In addition, this interface is likely to be questioned by customers as a backdoor, because the interface should not be exposed.

• CWE-1188

• https://github.com/liyansong2018/CVE/tree/main/2021/CVE-2021-34203Exploit, Third Party Advisory
• https://www.dlink.com/en/security-bulletin/Vendor Advisory
• https://github.com/liyansong2018/CVE/tree/main/2021/CVE-2021-34203Exploit, Third Party Advisory
• https://www.dlink.com/en/security-bulletin/Vendor Advisory

Published

Jun 16, 2021

Last Modified

Jul 9, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2021-3419Rejected reason: DO NOT USE THIS CANDIDATE NUMBER. ConsultID…
• CVE-2021-34190A stored cross site scripting (XSS) vulnerability in index.p…4.8
• CVE-2021-34193Stack overflow vulnerability in OpenSC smart card middleware…7.5
• CVE-2021-3420A flaw was found in newlib in versions prior to 4.0.0. Impro…9.8
• CVE-2021-34201D-Link DIR-2640-US 1.01B04 is vulnerable to Buffer Overflow.…7.1
• CVE-2021-34202There are multiple out-of-bounds vulnerabilities in some pro…7.8
• CVE-2021-34204D-Link DIR-2640-US 1.01B04 is affected by Insufficiently Pro…6.8
• CVE-2021-34207Cross-site scripting in ddns.htm in TOTOLINK A3002R version …6.1
• CVE-2021-3421A flaw was found in the RPM package in the read functionalit…5.5
• CVE-2021-34215Cross-site scripting in tcpipwan.htm in TOTOLINK A3002R vers…6.1
• CVE-2021-34218Directory Indexing in Login Portal of Login Portal of TOTOLI…5.3
• CVE-2021-3422The lack of validation of a key-value field in the Splunk-to…7.5