HTTP stack buffer overflow can enable code execution on TOTOLINK X2000R

Multiple exploitable stack-based buffer overflow vulnerabilities exist in the boa formFilter functionality of X2000R (version(s): TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327). A specially crafted HTTP request can lead to arbitrary code execution. An attacker can make an authenticated HTTP request to trigger these vulnerabilities. This vulnerability deals with the vpnPassword parameter.

The available evidence supports the following affected scope:

• TOTOLINK X2000R firmware TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327: affected.

The record does not provide additional affected branches or a fixed release. A different firmware should not be assumed to be fixed solely because its version number is newer.

TOTOLINK X2000R uses the boa web administration binary to process configuration requests. Talos reports that the relevant flow begins after successful authentication through /boafrm/formLogin, after which the requester can interact with /boafrm/formFilter and its callback. In formFilter(), the attacker-controlled vpnPassword value is read from the HTTP POST body and copied into a stack-local variable with an unbounded strcpy, creating a stack-based buffer overflow. The vulnerable path requires addFilterIP to be non-zero and the enabled parameter to be set before the affected code path is reached. Successful exploitation can result in arbitrary code execution or command execution. The available evidence does not establish the exact privilege level of the resulting code, the firmware's memory-protection behavior, or the scope of effects beyond the router.

The vulnerability can be triggered over the network with a specially crafted HTTP request. The attacker must authenticate first, so a valid administrative account or session is required; no separate user interaction is described. The record characterizes the attack complexity as low and the required privileges as high. Talos documented a crash condition and describes copying vpnPassword with strcpy as leading to possible code execution. The supplied record does not identify a public exploit, and the evidence does not establish in-the-wild exploitation.

An authenticated HTTP request can corrupt the boa process stack and lead to arbitrary code execution on the router. This could let an attacker control or disrupt management and networking functions, with potential effects on confidentiality, integrity, and availability. Because high privileges are required, the attacker must first pass the administrative authentication barrier; however, the record does not establish the exact post-exploitation privilege level or whether effects extend to other systems. No specific incident, victim, or stolen data is confirmed.

Successful exploitation can compromise the router's confidentiality, integrity, and availability. An attacker could execute code on the device and may then be able to alter configuration, disrupt network services, or affect traffic handled by the router; these are possible consequences rather than confirmed events in the record. Because the vulnerability requires administrative authentication, protecting credentials and limiting management access directly reduces exposure. The record does not identify a specific victim, campaign, intrusion, or data loss event.

1. Replace firmware TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327 with firmware that TOTOLINK confirms as fixed when such a release is available. No exact fixed release is established by the supplied evidence.
2. Until fixed firmware is available, restrict the web administration interface to trusted management networks and block unnecessary access from untrusted networks.
3. Review administrative accounts, remove accounts or sessions that are no longer needed, and ensure administrative credentials are not shared or reused.
4. After upgrading, recheck the model, firmware, and access controls for /boafrm/formFilter; do not treat an unverified version as fixed.

1. Inventory all TOTOLINK routers and firmware, then compare the exact version string listed in affected_summary.
2. Identify devices with web administration enabled and determine whether /boafrm/formFilter is reachable from untrusted networks.
3. If access logs retain POST field names or request content, review authenticated requests to /boafrm/formFilter containing vpnPassword; treat this as an investigation lead, not a confirmed IOC.
4. Review reboot, crash, and process-fault records associated with /bin/boa, together with unexpected router configuration changes.
5. Do not treat the absence of logs or crashes as proof of safety, because logging depends on the firmware and monitoring configuration.