CVE-2021-27255

Unauthenticated root code execution via unguarded service start

Published Mar 5, 2021 · Updated Aug 3, 2024

Missing authentication in NETGEAR R7800 firmware 1.0.2.76 allows remote attackers to execute arbitrary code through refresh_status.aspx. The endpoint accepts an unauthenticated request to start a server service, which reaches code execution in the root context. Exploitation requires network adjacency but no credentials or user interaction, and compromise grants root control of the router.

CVSS severity6.3
Medium
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authentication in NETGEAR R7800 firmware 1.0.2.76 allows remote attackers to execute arbitrary code through refresh_status.aspx. The endpoint accepts an unauthenticated request to start a server service, which reaches code execution in the root context. Exploitation requires network adjacency but no credentials or user interaction, and compromise grants root control of the router.

The record

CVE
CVE-2021-27255
Published
Mar 5, 2021
Updated
Aug 3, 2024
Vendor
NETGEAR
Product
R7800
Classifications
CWE-306, T1210
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

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
6.3Zero Day InitiativeCVSS: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-306Missing Authentication for Critical Function
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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