high
8.8
CWE
78
Advisory Published
Updated
Advisory Published

CVE-2021-27256: (Pwn2Own) NETGEAR R7800 apply_save.cgi rc_service Command Injection Remote Code Execution Vulnerability

First published: Fri Mar 05 2021(Updated: )

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R7800 firmware version 1.0.2.76. Although authentication is required to exploit this vulnerability, the existing authentication mechanism can be bypassed. The specific flaw exists within the handling of the rc_service parameter provided to apply_save.cgi. The issue results from the lack of proper validation of a user-supplied string before using it to execute a system call. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-12355.

Credit: zdi-disclosures@trendmicro.com

Affected SoftwareAffected VersionHow to fix
NETGEAR R7800 firmware
NETGEAR BR200<5.10.0.5
NETGEAR BR200
NETGEAR BR500 Firmware<5.10.0.5
NETGEAR br500 firmware
NETGEAR D7800<1.0.1.60
NETGEAR D7800 Firmware
NETGEAR EX6100v2 firmware<1.0.1.98
NETGEAR EX6100v2 firmware
NETGEAR EX6150v2 firmware<1.0.1.98
NETGEAR EX6150v2 firmware
NETGEAR EX6250<1.0.0.134
NETGEAR EX6250
NETGEAR EX6400<1.0.2.158
NETGEAR EX6400v2
NETGEAR EX6400v2 firmware<1.0.0.134
NETGEAR EX6400v2 firmware
NETGEAR EX6410<1.0.0.134
NETGEAR EX6410
NETGEAR EX6420<1.0.0.134
NETGEAR EX6420
NETGEAR EX7300<1.0.2.158
NETGEAR EX7300v2
NETGEAR EX7300v2 firmware<1.0.0.134
NETGEAR EX7300v2 firmware
NETGEAR EX7320<1.0.0.134
NETGEAR EX7320
NETGEAR EX7700<1.0.0.216
NETGEAR EX7700
NETGEAR EX8000<1.0.1.232
NETGEAR EX8000
NETGEAR LBR20 firmware<2.6.3.50
NETGEAR LBR20 firmware
NETGEAR R7800 firmware<1.0.2.80
NETGEAR R7800 firmware
NETGEAR R8900 firmware<1.0.5.28
NETGEAR R8900
NETGEAR R9000 firmware<1.0.5.28
NETGEAR R9000 firmware
NETGEAR RBK12 firmware<2.7.2.104
NETGEAR RBK12 firmware
NETGEAR rbk13 firmware<2.7.2.104
NETGEAR rbk13 firmware
NETGEAR RBK14 Firmware<2.7.2.104
NETGEAR rbk14 firmware
NETGEAR RBK15 Firmware<2.7.2.104
NETGEAR RBK15 Firmware
NETGEAR RBK20 Router Firmware<2.6.2.104
NETGEAR Orbi RBK20
NETGEAR RBK23 Satellite Firmware<2.7.2.104
NETGEAR Orbi RBK23
NETGEAR RBK40 Satellite Firmware<2.6.2.104
NETGEAR RBK40 Satellite Firmware
NETGEAR RBK43<2.6.2.104
NETGEAR RBK43 Router Firmware
NETGEAR RBK43 Router Firmware<2.6.2.104
NETGEAR RBK43S Firmware
NETGEAR RBK44 Satellite Firmware<2.6.2.104
NETGEAR RBK44 Satellite Firmware
NETGEAR RBK50 firmware<2.7.2.104
NETGEAR Orbi RBK50
NETGEAR RBK53 Firmware<2.7.2.104
NETGEAR Orbi RBK53
NETGEAR RBR10 firmware<2.6.2.104
NETGEAR RBR10 firmware
NETGEAR RBR20<2.6.2.104
NETGEAR RBR20
NETGEAR CBR40 firmware<2.6.2.104
NETGEAR RBR40 firmware
NETGEAR RBR50 firmware<2.7.2.104
NETGEAR RBR50 firmware
NETGEAR RBS10<2.6.2.104
NETGEAR RBS10 firmware
NETGEAR RBS20<2.6.2.104
NETGEAR RBS20 firmware
NETGEAR RBS40 Firmware<2.6.2.104
NETGEAR RBS40 firmware
NETGEAR RBS50 Firmware<2.7.2.104
NETGEAR RBS50 Firmware
NETGEAR RBS50Y firmware<2.6.2.104
NETGEAR RBS50Y firmware
NETGEAR XR450 firmware<2.3.2.114
NETGEAR XR450 firmware
NETGEAR XR500 firmware<2.3.2.114
NETGEAR XR500 firmware
NETGEAR XR700<1.0.1.38
NETGEAR XR700 firmware

Remedy

https://kb.netgear.com/000062883/Security-Advisory-for-Multiple-Vulnerabilities-on-Some-Routers-Satellites-and-Extenders

Never miss a vulnerability like this again

Sign up to SecAlerts for real-time vulnerability data matched to your software, aggregated from hundreds of sources.

Read MoreStart Free Trial

Reference Links

Frequently Asked Questions

  • What is the severity of CVE-2021-27256?

    CVE-2021-27256 has been classified as a critical vulnerability due to its ability to allow arbitrary code execution by bypassing authentication.

  • How do I fix CVE-2021-27256?

    To mitigate CVE-2021-27256, users should update their NETGEAR R7800 firmware to version 1.0.2.80 or later.

  • What devices are affected by CVE-2021-27256?

    CVE-2021-27256 affects NETGEAR R7800 firmware version 1.0.2.76 and older, as well as several other NETGEAR devices listed in the advisory.

  • Can CVE-2021-27256 be exploited remotely?

    CVE-2021-27256 can be exploited by network-adjacent attackers, requiring them to have access on the same network.

  • Is authentication still required to exploit CVE-2021-27256?

    Yes, although authentication is required, the existing mechanism can be bypassed, making it critical to address this vulnerability.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2025 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203