CVE-2021-27252

Root code execution via DHCP opcode injection

Published Apr 14, 2021 · Updated Aug 3, 2024

OS command injection in NETGEAR R7800 firmware 1.0.2.76 allows network-adjacent attackers to execute arbitrary code as root. The udchpd service passes an unvalidated string from the vendor_specific DHCP opcode into a system call, permitting command injection. Exploitation requires only adjacency to the router's network; no authentication or user interaction is required, and successful commands run with root privileges.

CVSS severity8.8
High
EPSS probability1.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in NETGEAR R7800 firmware 1.0.2.76 allows network-adjacent attackers to execute arbitrary code as root. The udchpd service passes an unvalidated string from the vendor_specific DHCP opcode into a system call, permitting command injection. Exploitation requires only adjacency to the router's network; no authentication or user interaction is required, and successful commands run with root privileges.

The record

CVE
CVE-2021-27252
Published
Apr 14, 2021
Updated
Aug 3, 2024
Vendor
NETGEAR
Product
R7800
Classifications
CWE-78, T1210
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=firmware version 1.0.2.76

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

NETGEAR · R7800version=firmware version 1.0.2.76

Published CVSS scores

8.3NIST NVDAV:A/AC:L/Au:N/C:C/I:C/A:C
8.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8Zero Day InitiativeCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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