https://feed.craftedsignal.io/products/n300rh-3.2.4-b20220812/Trending threats, MITRE ATT&CK coverage, and detection metadata — refreshed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioMon, 04 May 2026 10:16:01 +0000https://feed.craftedsignal.io/briefs/2026-05-totolink-n300rh-buffer-overflow/Mon, 04 May 2026 10:16:01 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-05-totolink-n300rh-buffer-overflow/A buffer overflow vulnerability exists in Totolink N300RH version 3.2.4-B20220812, specifically affecting the setWanConfig function within the /cgi-bin/cstecgi.cgi file, allowing a remote attacker to exploit it by manipulating the priDns argument in a POST request.A buffer overflow vulnerability has been identified in Totolink N300RH router version 3.2.4-B20220812. The vulnerability resides in the setWanConfig function within the /cgi-bin/cstecgi.cgi file, which handles POST requests. An attacker can exploit this vulnerability by manipulating the priDns argument in a crafted POST request. The vulnerability allows for remote exploitation, meaning an attacker does not need local access to the device. Public exploits for this vulnerability are already available, increasing the risk of exploitation. This vulnerability was published on 2026-05-04.

Attack Chain

1. The attacker identifies a vulnerable Totolink N300RH router running firmware version 3.2.4-B20220812.
2. The attacker crafts a malicious POST request targeting the /cgi-bin/cstecgi.cgi endpoint.
3. Within the POST request, the attacker includes the priDns argument with a value exceeding the buffer size.
4. The setWanConfig function processes the priDns argument without proper bounds checking.
5. The oversized priDns value overwrites adjacent memory on the stack, potentially including control flow data.
6. The attacker gains control of the program execution flow by overwriting the return address.
7. The attacker executes arbitrary code on the router, potentially gaining a shell.
8. The attacker could then use the compromised router to perform lateral movement, exfiltrate data, or establish a persistent backdoor.

Impact

Successful exploitation of this buffer overflow vulnerability can lead to complete compromise of the Totolink N300RH router. An attacker could gain unauthorized access to the device’s configuration, intercept network traffic, or use the router as a pivot point to attack other devices on the network. Given that public exploits are available, a wide range of attackers could potentially exploit this vulnerability. The CVSS v3.1 base score is 8.8 (HIGH).

Recommendation

• Monitor web server logs for POST requests to /cgi-bin/cstecgi.cgi with abnormally long priDns values to detect potential exploitation attempts using the provided Sigma rule.
• Implement network intrusion detection system (NIDS) rules to detect and block malicious POST requests targeting /cgi-bin/cstecgi.cgi.
• Contact Totolink for a security patch or firmware update to address CVE-2026-7749.

]]>highadvisorybuffer-overflowroutercve-2026-7749https://feed.craftedsignal.io/briefs/2026-05-totolink-buffer-overflow/Mon, 04 May 2026 10:16:01 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-05-totolink-buffer-overflow/A buffer overflow vulnerability exists in Totolink N300RH 3.2.4-B20220812 allowing remote attackers to execute arbitrary code by manipulating the mac_address argument in the setMacFilterRules function of the /cgi-bin/cstecgi.cgi POST request handler.A buffer overflow vulnerability, identified as CVE-2026-7750, affects Totolink N300RH router version 3.2.4-B20220812. The vulnerability resides in the setMacFilterRules function within the /cgi-bin/cstecgi.cgi file, which handles POST requests. Attackers can exploit this flaw by sending a specially crafted POST request with an overly long mac_address parameter, triggering a buffer overflow. Successful exploitation allows for arbitrary code execution on the device. The vulnerability is remotely exploitable, and a public exploit is available, increasing the risk of widespread attacks. Defenders should prioritize patching or mitigating this vulnerability to prevent potential compromise of affected devices.

Attack Chain

1. The attacker identifies a vulnerable Totolink N300RH router running firmware version 3.2.4-B20220812.
2. The attacker crafts a malicious POST request targeting the /cgi-bin/cstecgi.cgi endpoint.
3. Within the POST request, the attacker includes the mac_address parameter, injecting a string longer than the buffer allocated for it.
4. The setMacFilterRules function processes the POST request without proper bounds checking on the mac_address argument.
5. The overly long mac_address value overflows the buffer, overwriting adjacent memory regions.
6. The attacker carefully crafts the overflow to overwrite the return address, redirecting execution flow to attacker-controlled code.
7. The injected code executes with the privileges of the web server, allowing the attacker to execute arbitrary commands.
8. The attacker gains complete control over the router, potentially using it for further malicious activities such as network pivoting, data exfiltration, or denial-of-service attacks.

Impact

Successful exploitation of CVE-2026-7750 allows a remote attacker to execute arbitrary code on the vulnerable Totolink N300RH device. This could lead to a complete compromise of the router, allowing the attacker to control network traffic, steal sensitive information, or use the router as a bot in a larger attack. Given the public availability of the exploit, a large number of unpatched devices could be vulnerable to automated attacks, potentially impacting thousands of users.

Recommendation

• Apply available patches or firmware updates provided by Totolink to address CVE-2026-7750.
• Implement network intrusion detection system (IDS) rules to detect and block suspicious POST requests targeting the /cgi-bin/cstecgi.cgi endpoint with excessively long mac_address parameters.
• Deploy the Sigma rules in this brief to your SIEM to detect exploitation attempts.
• Monitor web server logs for unusual POST requests to /cgi-bin/cstecgi.cgi, focusing on requests with large mac_address values.

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