{"id":"CVE-2021-27239","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-27239","generatedAt":"2026-10-27T23:27:12.163Z","title":"This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R6400 and R6700 firmware version 1.0.4.98 routers.","description":"This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R6400 and R6700 firmware version 1.0.4.98 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the upnpd service, which listens on UDP port 1900 by default. A crafted MX header field in an SSDP message can trigger an overflow of a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-11851.","published":"2021-03-29T21:15:12.000Z","lastModified":"2026-06-17T03:44:31.000Z","status":"Modified","sourceIdentifier":"zdi-disclosures@trendmicro.com","cvss":{"version":"3.1","score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-121"],"affected":["netgear/d6220 firmware","netgear/d6400 firmware","netgear/d7000 firmware","netgear/d8500 firmware","netgear/dc112a firmware","netgear/ex7000 firmware","netgear/ex7500 firmware","netgear/r6250 firmware","netgear/r6300 firmware","netgear/r6400 firmware","netgear/r6700 firmware","netgear/r6900p firmware","netgear/r7000 firmware","netgear/r7000p firmware","netgear/r7100lg firmware","netgear/r7850 firmware","netgear/r7900 firmware","netgear/r7900p firmware","netgear/r7960p firmware","netgear/r8000 firmware","netgear/r8000p firmware","netgear/r8300 firmware","netgear/r8500 firmware","netgear/rax200 firmware","netgear/rax75 firmware","netgear/rax80 firmware","netgear/rbr750 firmware","netgear/rbr850 firmware","netgear/rbs40v firmware","netgear/rbs750 firmware","netgear/rbs850 firmware","netgear/rs400 firmware","netgear/wndr3400 firmware","netgear/wnr3500l firmware","netgear/xr300 firmware"],"epss":{"score":0.00766,"percentile":0.55216,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.77%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://kb.netgear.com/000062820/Security-Advisory-for-Stack-based-Buffer-Overflow-Remote-Code-Execution-Vulnerability-on-Some-Routers-PSV-2020-0432","tags":["Vendor Advisory"],"source":"zdi-disclosures@trendmicro.com"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-206/","tags":["Third Party Advisory","VDB Entry"],"source":"zdi-disclosures@trendmicro.com"},{"url":"https://kb.netgear.com/000062820/Security-Advisory-for-Stack-based-Buffer-Overflow-Remote-Code-Execution-Vulnerability-on-Some-Routers-PSV-2020-0432","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-206/","tags":["Third Party Advisory","VDB Entry"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-27239","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}