CVE Alert: CVE-2025-9781 – TOTOLINK – A702R

Risk verdict

High risk: remote code execution on TOTOLINK A702R via a buffer overflow with a publicly disclosed exploit; ensure devices exposed to the network are patched promptly.

Why this matters

The flaw allows unauthenticated network access to trigger memory corruption, potentially yielding control of the device. In environments where routers form the perimeter or internal segmentation relies on these devices, attacker footholds could enable monitoring, traffic manipulation, or pivot into connected hosts.

Most likely attack path

An attacker can reach the vulnerable formFilter routine over the network (AV:N, UI:N), exploiting the crafted ip6addr input to cause overflow (C:H/I:H/A:H). Exploitation runs with low-priority privileges but can compromise the appliance itself, providing high-impact control of routing and data paths. Scope remains unchanged, so the attacker may abuse the device without requiring a full trust boundary break, facilitating rapid impact within the targeted network.

Who is most exposed

Consumer and SMB deployments of TOTOLINK A702R, especially where the device is internet-facing or remote management is enabled, are at greatest risk. Networks relying on this model as the primary router or gateway are prime targets.

Detection ideas

• Unexpected device reboots or memory corruption crashes in logs.
• Anomalous traffic patterns targeting the management interface or formFilter endpoints.
• IDS/IPS signatures for known payloads or IP6addr-like crafting attempts.
• Unusual CPU/memory spikes on the device.

Mitigation and prioritisation

• Apply the vendor patch (update to 4.0.0-B20211108.1423 or newer) immediately.
• Disable remote management or restrict access to trusted networks; implement tight ACLs and firewall rules.
• Segment and isolate the router management plane from user traffic; consider temporary compensating controls (WAF, reverse proxy) if patching cannot be applied promptly.
• Plan a change window for deployment and verification in staging before production rollout.
• If KEV true or EPSS ≥ 0.5 (not provided here), treat as priority 1; otherwise categorise as high priority given CVSS severity.