{"cve":"CVE-2021-27239","nvd":{"published":"2021-03-29T21:15:12.377","modified":"2026-06-17T03:44:31.490","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-121"],"references":["https://kb.netgear.com/000062820/Security-Advisory-for-Stack-based-Buffer-Overflow-Remote-Code-Execution-Vulnerability-on-Some-Routers-PSV-2020-0432","https://www.zerodayinitiative.com/advisories/ZDI-21-206/","https://kb.netgear.com/000062820/Security-Advisory-for-Stack-based-Buffer-Overflow-Remote-Code-Execution-Vulnerability-on-Some-Routers-PSV-2020-0432","https://www.zerodayinitiative.com/advisories/ZDI-21-206/"],"products":["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"],"source":"nvd","synced_at":"2026-10-19T21:17:01.373894544+00:00"},"epss":{"cve":"CVE-2021-27239","score":0.00766,"percentile":0.555,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}