{"cve":"CVE-2021-40847","nvd":{"published":"2021-09-21T18:15:07.377","modified":"2026-06-17T04:07:31.783","status":"Modified","description":"The update process of the Circle Parental Control Service on various NETGEAR routers allows remote attackers to achieve remote code execution as root via a MitM attack. While the parental controls themselves are not enabled by default on the routers, the Circle update daemon, circled, is enabled by default. This daemon connects to Circle and NETGEAR to obtain version information and updates to the circled daemon and its filtering database. However, database updates from NETGEAR are unsigned and downloaded via cleartext HTTP. As such, an attacker with the ability to perform a MitM attack on the device can respond to circled update requests with a crafted, compressed database file, the extraction of which gives the attacker the ability to overwrite executable files with attacker-controlled code. This affects R6400v2 1.0.4.106, R6700 1.0.2.16, R6700v3 1.0.4.106, R6900 1.0.2.16, R6900P 1.3.2.134, R7000 1.0.11.123, R7000P 1.3.2.134, R7850 1.0.5.68, R7900 1.0.4.38, R8000 1.0.4.68, and RS400 1.5.0.68.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.1},"cwes":["CWE-319"],"references":["https://blog.grimm-co.com/2021/09/mama-always-told-me-not-to-trust.html","https://kb.netgear.com/000064039/Security-Advisory-for-Remote-Code-Execution-on-Some-Routers-PSV-2021-0204","https://blog.grimm-co.com/2021/09/mama-always-told-me-not-to-trust.html","https://kb.netgear.com/000064039/Security-Advisory-for-Remote-Code-Execution-on-Some-Routers-PSV-2021-0204"],"products":["netgear:r6400v2_firmware","netgear:r6700_firmware","netgear:r6700v3_firmware","netgear:r6900_firmware","netgear:r6900p_firmware","netgear:r7000_firmware","netgear:r7000p_firmware","netgear:r7850_firmware","netgear:r7900_firmware","netgear:r8000_firmware","netgear:rs400_firmware"],"source":"nvd","synced_at":"2026-10-19T21:23:41.316049955+00:00"},"epss":{"cve":"CVE-2021-40847","score":0.10014,"percentile":0.95614,"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."]}