HOMEVULNERABILITIESCVE-2021-27251
HIGH

CVE-2021-27251

CWE-319Published: April 14, 2021· Updated: Jun 17, 2026

8.8
CVSS v3.1

Official Description

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR Nighthawk R7800. Authentication is not required to exploit this vulnerability The specific flaw exists within handling of firmware updates. The issue results from a fallback to a insecure protocol to deliver updates. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-12308.

NVD Source

Technical Analysis

CVE-2021-27251 requires adjacent network access, limiting remote exploitation but still posing risk in shared or local network environments.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorAdjacent
Attack ComplexityLow
Privileges Req.None
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

Affected Vendors & Products

netgear84 product(s)
br200 firmwarebr200br500 firmwarebr500d7800 firmwared7800ex6100v2 firmwareex6100ex6150 firmwareex6150ex6250 firmwareex6250+72
Source: NVD CPE · 86 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://kb.netgear.com/000062883/Security-Advisory-for-Multiple-Vulnerabilities-on-Some-Routers-Satellites-and-Extenders
PATCHhttps://kb.netgear.com/000062883/Security-Advisory-for-Multiple-Vulnerabilities-on-Some-Routers-Satellites-and-Extenders
ADVISORYhttps://www.zerodayinitiative.com/advisories/ZDI-21-247/
ADVISORYhttps://www.zerodayinitiative.com/advisories/ZDI-21-247/

All References (4)

→
https://kb.netgear.com/000062883/Security-Advisory-for-Multiple-Vulnerabilities-on-Some-Routers-Satellites-and-ExtendersPatch · Vendor Advisory
→
https://www.zerodayinitiative.com/advisories/ZDI-21-247/Third Party Advisory · VDB Entry
→
https://kb.netgear.com/000062883/Security-Advisory-for-Multiple-Vulnerabilities-on-Some-Routers-Satellites-and-ExtendersPatch · Vendor Advisory
→
https://www.zerodayinitiative.com/advisories/ZDI-21-247/Third Party Advisory · VDB Entry

Quick Facts

CVE IDCVE-2021-27251
CVSS Score8.8 / 10
SeverityHIGH
WeaknessCWE-319
CISA KEVNo
Affected1 vendor(s)
PublishedApr 14, 2021

Related CVEs (CWE-319)

CVE-2025-47419
10.0
CVE-2025-4378
10.0
CVE-2023-32328
9.8
CVE-2025-32880
9.8
CVE-2025-26199
9.8
CVE-2016-5649
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-27251 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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