TI-2021-13309 Aliases CVE-2021-34203 GHSA-gr4j-7v97-rrfc

D-Link DIR-2640-US 1.01B04 is vulnerable to Incorrect Access Control.

LOW 38CWE-1188Published 2021-06-16 · Updated 2026-07-09

Key facts

Attack vector: Adjacent network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: High · High · None
Fix status: No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

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.

Why it matters now

EPSS 0.01195 68th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix No fix listed No fixed version in the sources yet

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
—	—	all versions	—	No fix listed	CNA

— Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPE	Versions	Role	Vendor
cpe:2.3:o:dlink:dir-2640-us_firmware:1.01b04:::::::*	1.01b04	Vulnerable	D-Link Japan K.K.
cpe:2.3:h:dlink:dir-2640-us:-:::::::*	not specified by NVD	Running on	D-Link Japan K.K.

cpe:2.3:o:dlink:dir-2640-us_firmware:1.01b04:*:*:*:*:*:*:* Versions 1.01b04 Vulnerable ·D-Link Japan K.K.
cpe:2.3:h:dlink:dir-2640-us:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·D-Link Japan K.K.

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2021-34203
2026-10-03 Alias added: GHSA-gr4j-7v97-rrfc

References

Exploit 1

https://github.com/liyansong2018/CVE/tree/main/2021/CVE-2021-34203

Advisory 1

https://www.dlink.com/en/security-bulletin/

TI-2021-03434 Path traversal in Quagga Services on D-Link DIR-2640 Routers CVSS 3.1HIGH 8.4
TI-2021-03432 Hard-coded credentials in Quagga Services on D-Link DIR-2640 Routers CVSS 3.1HIGH 8.8
TI-2021-13308 There are multiple out-of-bounds vulnerabilities in some processes of D-Link… CVSS 3.1HIGH 7.8
TI-2021-13310 D-Link DIR-2640-US 1.01B04 is affected by Insufficiently Protected Credentials. CVSS 3.1MEDIUM 6.8
TI-2021-13307 D-Link DIR-2640-US 1.01B04 is vulnerable to Buffer Overflow. CVSS 3.1HIGH 7.1
TI-2021-03433 Path traversal in Quagga Services on D-Link DIR-2640 Routers CVSS 3.1MEDIUM 6.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences