CVE & CISA-KEV Catalog

CVE-2021-27256

HIGH
8.8
CVSS v3
NVD

Description

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.

CWE-78OS Command Injection

How to fix

Remediation Available
br200 firmwareNVD
Affected:< 5.10.0.5Fixed in:5.10.0.5CVE-2021-27256derived from NVD
br500 firmwareNVD
Affected:< 5.10.0.5Fixed in:5.10.0.5CVE-2021-27256derived from NVD
d7800 firmwareNVD
Affected:< 1.0.1.60Fixed in:1.0.1.60CVE-2021-27256derived from NVD
ex6100v2 firmwareNVD
Affected:< 1.0.1.98Fixed in:1.0.1.98CVE-2021-27256derived from NVD
ex6150v2 firmwareNVD
Affected:< 1.0.1.98Fixed in:1.0.1.98CVE-2021-27256derived from NVD
ex6250 firmwareNVD
Affected:< 1.0.0.134Fixed in:1.0.0.134CVE-2021-27256derived from NVD
ex6400 firmwareNVD
Affected:< 1.0.2.158Fixed in:1.0.2.158CVE-2021-27256derived from NVD
ex6400v2 firmwareNVD
Affected:< 1.0.0.134Fixed in:1.0.0.134CVE-2021-27256derived from NVD
ex6410 firmwareNVD
Affected:< 1.0.0.134Fixed in:1.0.0.134CVE-2021-27256derived from NVD
ex6420 firmwareNVD
Affected:< 1.0.0.134Fixed in:1.0.0.134CVE-2021-27256derived from NVD
ex7300 firmwareNVD
Affected:< 1.0.2.158Fixed in:1.0.2.158CVE-2021-27256derived from NVD
ex7300v2 firmwareNVD
Affected:< 1.0.0.134Fixed in:1.0.0.134CVE-2021-27256derived from NVD
ex7320 firmwareNVD
Affected:< 1.0.0.134Fixed in:1.0.0.134CVE-2021-27256derived from NVD
ex7700 firmwareNVD
Affected:< 1.0.0.216Fixed in:1.0.0.216CVE-2021-27256derived from NVD
ex8000 firmwareNVD
Affected:< 1.0.1.232Fixed in:1.0.1.232CVE-2021-27256derived from NVD
lbr20 firmwareNVD
Affected:< 2.6.3.50Fixed in:2.6.3.50CVE-2021-27256derived from NVD
r7800 firmwareNVD
Affected:< 1.0.2.80Fixed in:1.0.2.80CVE-2021-27256derived from NVD
r8900 firmwareNVD
Affected:< 1.0.5.28Fixed in:1.0.5.28CVE-2021-27256derived from NVD
r9000 firmwareNVD
Affected:< 1.0.5.28Fixed in:1.0.5.28CVE-2021-27256derived from NVD
rbk12 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbk13 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbk14 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbk15 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbk20 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbk23 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbk40 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbk43 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbk43s firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbk44 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbk50 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbk53 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbr10 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbr20 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbr40 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbr50 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbs10 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbs20 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbs40 firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
rbs50 firmwareNVD
Affected:< 2.7.2.104Fixed in:2.7.2.104CVE-2021-27256derived from NVD
rbs50y firmwareNVD
Affected:< 2.6.2.104Fixed in:2.6.2.104CVE-2021-27256derived from NVD
xr450 firmwareNVD
Affected:< 2.3.2.114Fixed in:2.3.2.114CVE-2021-27256derived from NVD
xr500 firmwareNVD
Affected:< 2.3.2.114Fixed in:2.3.2.114CVE-2021-27256derived from NVD
xr700 firmwareNVD
Affected:< 1.0.1.38Fixed in:1.0.1.38CVE-2021-27256derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorAdjacent
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

0.87%probability of exploitation in 30 days
54thpercentile

Moderate risk: more likely to be exploited than 54% of all known CVEs.

References

Third-Party Advisory1

Related Vulnerabilities

Other CWE-78 (OS Command Injection) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2021-1498Critical9.8100%KEVFix
CVE-2014-6271Critical9.8100%KEVFix
CVE-2019-16920Critical9.8100%KEV-
CVE-2022-44877Critical9.8100%KEVFix
CVE-2020-8515Critical9.8100%KEV-
CVE-2020-9054Critical9.8100%KEVFix
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.