CVE-2021-27256 : This vulnerability allows network-adjacent attackers to execute arbitrary code o

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.

Published 2021-03-05 20:15:13

Updated 2021-03-16 19:35:10

Source Zero Day Initiative

View at NVD, CVE.org

Vulnerability category: Execute code

Products affected by CVE-2021-27256

Netgear » R7800 Firmware
Versions before (<) 1.0.2.80
cpe:2.3:o:netgear:r7800_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » R7800 » Version: N/A
Netgear » R9000 Firmware
Versions before (<) 1.0.5.28
cpe:2.3:o:netgear:r9000_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » R9000 » Version: N/A
Netgear » D7800 Firmware
Versions before (<) 1.0.1.60
cpe:2.3:o:netgear:d7800_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » D7800 » Version: N/A
Netgear » Ex6400 Firmware
Versions before (<) 1.0.2.158
cpe:2.3:o:netgear:ex6400_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex6400 » Version: N/A
Netgear » Ex7300 Firmware
Versions before (<) 1.0.2.158
cpe:2.3:o:netgear:ex7300_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex7300 » Version: N/A
Netgear » Ex8000 Firmware
Versions before (<) 1.0.1.232
cpe:2.3:o:netgear:ex8000_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex8000 » Version: N/A
Netgear » R8900 Firmware
Versions before (<) 1.0.5.28
cpe:2.3:o:netgear:r8900_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » R8900 » Version: N/A
Netgear » Xr500 Firmware
Versions before (<) 2.3.2.114
cpe:2.3:o:netgear:xr500_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Xr500 » Version: N/A
Netgear » Xr700 Firmware
Versions before (<) 1.0.1.38
cpe:2.3:o:netgear:xr700_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Xr700 » Version: N/A
Netgear » Rbr20 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbr20_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbr20 » Version: N/A
Netgear » Rbs20 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbs20_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbs20 » Version: N/A
Netgear » Rbk20 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbk20_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk20 » Version: N/A
Netgear » Rbr40 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbr40_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbr40 » Version: N/A
Netgear » Rbs40 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbs40_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbs40 » Version: N/A
Netgear » Rbk40 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbk40_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk40 » Version: N/A
Netgear » Rbr50 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbr50_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbr50 » Version: N/A
Netgear » Rbs50 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbs50_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbs50 » Version: N/A
Netgear » Rbk50 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbk50_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk50 » Version: N/A
Netgear » Xr450 Firmware
Versions before (<) 2.3.2.114
cpe:2.3:o:netgear:xr450_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Xr450 » Version: N/A
Netgear » Br200 Firmware
Versions before (<) 5.10.0.5
cpe:2.3:o:netgear:br200_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Br200 » Version: N/A
Netgear » Br500 Firmware
Versions before (<) 5.10.0.5
cpe:2.3:o:netgear:br500_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Br500 » Version: N/A
Netgear » Ex6100v2 Firmware
Versions before (<) 1.0.1.98
cpe:2.3:o:netgear:ex6100v2_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex6100v2 » Version: N/A
Netgear » Ex6150v2 Firmware
Versions before (<) 1.0.1.98
cpe:2.3:o:netgear:ex6150v2_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex6150v2 » Version: N/A
Netgear » Ex6250 Firmware
Versions before (<) 1.0.0.134
cpe:2.3:o:netgear:ex6250_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex6250 » Version: N/A
Netgear » Ex6400v2 Firmware
Versions before (<) 1.0.0.134
cpe:2.3:o:netgear:ex6400v2_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex6400v2 » Version: N/A
Netgear » Ex6410 Firmware
Versions before (<) 1.0.0.134
cpe:2.3:o:netgear:ex6410_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex6410 » Version: N/A
Netgear » Ex6420 Firmware
Versions before (<) 1.0.0.134
cpe:2.3:o:netgear:ex6420_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex6420 » Version: N/A
Netgear » Ex7300v2 Firmware
Versions before (<) 1.0.0.134
cpe:2.3:o:netgear:ex7300v2_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex7300v2 » Version: N/A
Netgear » Ex7320 Firmware
Versions before (<) 1.0.0.134
cpe:2.3:o:netgear:ex7320_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex7320 » Version: N/A
Netgear » Ex7700 Firmware
Versions before (<) 1.0.0.216
cpe:2.3:o:netgear:ex7700_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Ex7700 » Version: N/A
Netgear » Lbr20 Firmware
Versions before (<) 2.6.3.50
cpe:2.3:o:netgear:lbr20_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Lbr20 » Version: N/A
Netgear » Rbk12 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbk12_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk12 » Version: N/A
Netgear » Rbk13 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbk13_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk13 » Version: N/A
Netgear » Rbk14 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbk14_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk14 » Version: N/A
Netgear » Rbk15 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbk15_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk15 » Version: N/A
Netgear » Rbk23 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbk23_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk23 » Version: N/A
Netgear » Rbk43 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbk43_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk43 » Version: N/A
Netgear » Rbk43s Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbk43s_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk43s » Version: N/A
Netgear » Rbk44 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbk44_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk44 » Version: N/A
Netgear » Rbk53 Firmware
Versions before (<) 2.7.2.104
cpe:2.3:o:netgear:rbk53_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbk53 » Version: N/A
Netgear » Rbr10 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbr10_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbr10 » Version: N/A
Netgear » Rbs10 Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbs10_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbs10 » Version: N/A
Netgear » Rbs50y Firmware
Versions before (<) 2.6.2.104
cpe:2.3:o:netgear:rbs50y_firmware:*:*:*:*:*:*:*:*
Matching versions
When used together with: Netgear » Rbs50y » Version: N/A

Exploit prediction scoring system (EPSS) score for CVE-2021-27256

EPSS FAQ

0.41%

Probability of exploitation activity in the next 30 days EPSS Score History

~ 58 %

Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2021-27256

Base Score	Base Severity	CVSS Vector	Exploitability Score	Impact Score	Score Source
8.3	HIGH	AV:A/AC:L/Au:N/C:C/I:C/A:C	6.5	10.0	NIST
Access Vector: Adjacent Network Access Complexity: Low Authentication: None Confidentiality Impact: Complete Integrity Impact: Complete Availability Impact: Complete
8.8	HIGH	CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	2.8	5.9	Zero Day Initiative
Attack Vector: Adjacent Network Attack Complexity: Low Privileges Required: None User Interaction: None Scope: Unchanged Confidentiality: High Integrity: High Availability: High
8.8	HIGH	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	2.8	5.9	NIST
Attack Vector: Adjacent Network Attack Complexity: Low Privileges Required: None User Interaction: None Scope: Unchanged Confidentiality: High Integrity: High Availability: High

CWE ids for CVE-2021-27256

CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Assigned by: zdi-disclosures@trendmicro.com (Primary)

References for CVE-2021-27256

https://www.zerodayinitiative.com/advisories/ZDI-21-262/

ZDI-21-262 | Zero Day Initiative
Third Party Advisory;VDB Entry
https://kb.netgear.com/000062883/Security-Advisory-for-Multiple-Vulnerabilities-on-Some-Routers-Satellites-and-Extenders

Security Advisory for Multiple Vulnerabilities on Some Routers, Satellites, and Extenders | Answer | NETGEAR Support
Patch;Vendor Advisory

CVEs referencing this url

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Vulnerability Details : CVE-2021-27256

Products affected by CVE-2021-27256

Exploit prediction scoring system (EPSS) score for CVE-2021-27256

CVSS scores for CVE-2021-27256

CWE ids for CVE-2021-27256

References for CVE-2021-27256