CVE-2021-27256
This vulnerability allows network-adjacent attackers to execute arbitrary code on affected...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2021-27256- CVSS 3.0
- 8.8 High
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-78
- Updated
- 2026-11-02
EUVDEUVD-2021-14021
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.
- Record
EUVD-2021-14021- CVSS 3.0
- 8.8 High
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-7j9h-j7vq-452x No score
This vulnerability allows network-adjacent attackers to execute arbitrary code on affected...
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.
- Record
GHSA-7j9h-j7vq-452x- Weakness
- CWE-78
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-27256- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 3.0
- 8.8 High
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 8.3 High
AV:A/AC:L/Au:N/C:C/I:C/A:C - Weakness
- CWE-78
- Updated
- 2026-11-02
Affected products
- netgear r7800
- netgear r7800 firmware
- netgear br200 firmware
- netgear br500 firmware
- netgear d7800 firmware
- netgear ex6100v2 firmware
- netgear ex6150v2 firmware
- netgear ex6250 firmware
- netgear ex6400 firmware
- netgear ex6400v2 firmware
- netgear ex6410 firmware
- netgear ex6420 firmware
Show 32 moreShow less
- netgear ex7300 firmware
- netgear ex7300v2 firmware
- netgear ex7320 firmware
- netgear ex7700 firmware
- netgear ex8000 firmware
- netgear lbr20 firmware
- netgear r8900 firmware
- netgear r9000 firmware
- netgear rbk12 firmware
- netgear rbk13 firmware
- netgear rbk14 firmware
- netgear rbk15 firmware
- netgear rbk20 firmware
- netgear rbk23 firmware
- netgear rbk40 firmware
- netgear rbk43 firmware
- netgear rbk43s firmware
- netgear rbk44 firmware
- netgear rbk50 firmware
- netgear rbk53 firmware
- netgear rbr10 firmware
- netgear rbr20 firmware
- netgear rbr40 firmware
- netgear rbr50 firmware
- netgear rbs10 firmware
- netgear rbs20 firmware
- netgear rbs40 firmware
- netgear rbs50 firmware
- netgear rbs50y firmware
- netgear xr450 firmware
- netgear xr500 firmware
- netgear xr700 firmware
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-27256 is a high vulnerability (CVSS 8.8) in Netgear R7800, published March 5, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.96%, the 61st percentile. No source names a fixed version.