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.

CVSS v3.1

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

CVSS v2.0

4.8 MEDIUMAV:A/AC:L/Au:N/C:P/I:P/A:N

EPSS

1.20% chance of exploitation in the next 30 days, 66th percentile

Published

2021-06-16

Updated

2026-07-09

Proof-of-concept exploits (1)

• liyansong2018/CVE/tree/main/2021/CVE-2021-34203

References

• CVE Record
• NVD entry

Related

• CVE-2021-29302
• CVE-2021-31658
• CVE-2021-31659
• CVE-2021-34201
• CVE-2021-34202
• CVE-2022-21711