{"id":"CVE-2021-31755","published":"2021-05-07T23:15:07Z","modified":"2026-06-17T03:52:12Z","title":"Tenda AC11 Router Stack Buffer Overflow Vulnerability","vendor":"Tenda","product":"AC11 Router","tier":"core","eol":null,"description":{"text":"An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /goform/setmac allows attackers to execute arbitrary code on the system via a crafted post request.","provenance":"source","from":"NVD"},"summary":{"text":"A stack buffer overflow in the /goform/setmac handler of the Tenda AC11 Router's firmware (through 02.03.01.104_CN) is the flaw. An attacker who can send a crafted POST request to the device, with no authentication or user interaction required, can execute arbitrary code on the router.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-29T07:11:10Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.86511,"percentile":0.99737,"date":"2026-10-30","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","ransomware":false,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-31755","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-06-24","exploitedFirstSeen":"2021-06-24","ransomware":false,"evidence":[{"url":"https://www.fortinet.com/blog/threat-research/the-ghosts-of-mirai","date":"2021-06-24"},{"url":"https://blogs.juniper.net/en-us/security/freshly-disclosed-vulnerability-cve-2021-20090-exploited-in-the-wild","date":"2021-08-06"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-22&host_type=src&vulnerability=cve-2021-31755","date":"2024-01-22"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-23&host_type=src&vulnerability=cve-2021-31755","date":"2024-01-23"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-24&host_type=src&vulnerability=cve-2021-31755","date":"2024-01-24"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-25&host_type=src&vulnerability=cve-2021-31755","date":"2024-01-25"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-26&host_type=src&vulnerability=cve-2021-31755","date":"2024-01-26"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-27&host_type=src&vulnerability=cve-2021-31755","date":"2024-01-27"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-28&host_type=src&vulnerability=cve-2021-31755","date":"2024-01-28"}],"evidenceTotal":731,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev 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2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-787","name":"Out-of-bounds Write"}],"references":[{"url":"https://github.com/Yu3H0/IoT_CVE/tree/main/Tenda/CVE_3","tags":["Broken Link","Exploit","Issue Tracking","Third Party Advisory"]},{"url":"https://github.com/Yu3H0/IoT_CVE/tree/main/Tenda/CVE_3","tags":["Broken Link","Exploit","Issue Tracking","Third Party Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31755","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing 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(quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-18639","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-18639","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":{"nuclei":[{"id":"CVE-2021-31755","name":"Tenda Router AC11 - Remote Command Injection","severity":"critical","path":"http/cves/2021/CVE-2021-31755.yaml","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-31755.yaml"}],"provenance":"source"},"exploitRefs":["https://github.com/Yu3H0/IoT_CVE/tree/main/Tenda/CVE_3"],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2021-05-07","kind":"published","label":"Published 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