CVE-2021-27254

Root code execution via hard-coded encryption key

Published Mar 5, 2021 · Updated Aug 3, 2024

Authentication bypass in NETGEAR R7800 firmware 1.0.2.76 allows network-adjacent attackers to execute arbitrary code as root. The apply_save.cgi endpoint relies on a hard-coded encryption key when authenticating requests, so a crafted request passes the check. Access from the router's local network is sufficient; no existing credentials or user interaction are required, and successful exploitation grants root-level execution.

CVSS severity6.3
Medium
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in NETGEAR R7800 firmware 1.0.2.76 allows network-adjacent attackers to execute arbitrary code as root. The apply_save.cgi endpoint relies on a hard-coded encryption key when authenticating requests, so a crafted request passes the check. Access from the router's local network is sufficient; no existing credentials or user interaction are required, and successful exploitation grants root-level execution.

The record

CVE
CVE-2021-27254
Published
Mar 5, 2021
Updated
Aug 3, 2024
Vendor
NETGEAR
Product
R7800
Classifications
CWE-259, T1190
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 5, 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

6.3Zero Day InitiativeCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
6.3NETGEARCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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-259Use of Hard-coded Password
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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