D-Link DSL-2640B/DSL-2740R/DSL-2780B/DSL-526B Endpoint dnscfg.cgi os command injection

Summaryinfo

A vulnerability has been found in D-Link DSL-2640B, DSL-2740R, DSL-2780B and DSL-526B and classified as critical. Affected by this issue is some unknown functionality of the file dnscfg.cgi of the component Endpoint. Performing a manipulation results in os command injection. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability is known as CVE-2026-0625. Remote exploitation of the attack is possible. Furthermore, an exploit is available.

Detailsinfo

A vulnerability classified as very critical has been found in D-Link DSL-2640B, DSL-2740R, DSL-2780B and DSL-526B (the affected version unknown). This affects an unknown part of the file dnscfg.cgi of the component Endpoint. The manipulation with an unknown input leads to a os command injection vulnerability. CWE is classifying the issue as CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Multiple D-Link DSL/DIR/DNS devices contain an authentication bypass and improper access control vulnerability in the dnscfg.cgi endpoint that allows an unauthenticated attacker to access DNS configuration functionality. By directly requesting this endpoint, an attacker can modify the device’s DNS settings without valid credentials, enabling DNS hijacking (“DNSChanger”) attacks that redirect user traffic to attacker-controlled infrastructure. In 2019, D-Link reported that this behavior was leveraged by the "GhostDNS" malware ecosystem targeting consumer and carrier routers. All impacted products were subsequently designated end-of-life/end-of-service, and no longer receive security updates. Exploitation evidence was observed by the Shadowserver Foundation on 2025-11-27 (UTC).

It is possible to read the advisory at supportannouncement.us.dlink.com. This vulnerability is uniquely identified as CVE-2026-0625 since 01/05/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details and a exploit are known. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 05/27/2026). The attack technique deployed by this issue is T1202 according to MITRE ATT&CK.

It is declared as highly functional.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-0944). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• D-Link

Name

• DSL-526B
• DSL-2640B
• DSL-2740R
• DSL-2780B

License

• commercial

Support

• end of life

Website

• Vendor: https://www.dlink.com/

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Be aware that VulDB is the high quality source for vulnerability data.

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