CVE Alert: CVE-2025-10666 – D-Link – DIR-825
CVE-2025-10666
A security flaw has been discovered in D-Link DIR-825 up to 2.10. Affected by this vulnerability is the function sub_4106d4 of the file apply.cgi. The manipulation of the argument countdown_time results in buffer overflow. The attack can be executed remotely. The exploit has been released to the public and may be exploited. This vulnerability only affects products that are no longer supported by the maintainer.
AI Summary Analysis
Risk verdict
High risk of remote code execution on affected D-Link DIR-825 devices; public exploit available, so urgent mitigation is warranted.
Why this matters
The DIR-825 sits at the network edge; compromise could lead to full control of the router, data exfiltration, DNS/config manipulation, and lateral movement to internal hosts. With vendor support ended, there are likely no patches, amplifying exposure across home and small business deployments still in use.
Most likely attack path
Exploitation is remote, requiring network access (no user interaction) with low-privilege prerequisites. An attacker can send crafted input to apply.cgi (countdown_time) to trigger a memory corruption vulnerability, potentially yielding arbitrary code execution with high impact. Because the vulnerability lies in a router component and the device operates within a trusted network, successful compromise enables immediate circuit-board control and potential LAN-wide access without user consent.
Who is most exposed
Devices in consumer or small-office networks that are no longer supported or patched are most at risk, particularly where remote management or public-facing admin interfaces were enabled.
Detection ideas
- Alerts for unusual HTTP requests to apply.cgi, especially countdown_time parameters.
- Logs showing router crashes or reboots following remote requests.
- IDS/IPS signatures or traffic patterns targeting DIR-825 apply.cgi endpoints.
- Unexpected admin session activity or config changes from WAN or unauthorised sources.
- Signatures or indicators referencing sub_4106d4 or similar memory-corruption patterns.
Mitigation and prioritisation
- Replace with supported hardware or upgrade to a firmware path still receiving updates; if unavailable, isolate or retire the device.
- Disable remote management and limit admin interfaces to trusted networks; enforce strong authentication controls.
- Implement network segmentation and firewall rules to block WAN access to the router’s management surface; restrict outbound management access.
- Remove or disable the vulnerable feature (apply.cgi) if feasible; apply compensating controls and monitor for exploitation indicators.
- Maintain an asset inventory and a decommission plan; consider impact assessments for any dependent services.
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