HOMEVULNERABILITIESCVE-2021-27257
MEDIUM

CVE-2021-27257

CWE-295Published: March 5, 2021· Updated: Jun 17, 2026

6.5
CVSS v3.1

Official Description

This vulnerability allows network-adjacent attackers to compromise the integrity of downloaded information on affected installations of NETGEAR R7800 firmware version 1.0.2.76. Authentication is not required to exploit this vulnerability. The specific flaw exists within the downloading of files via FTP. The issue results from the lack of proper validation of the certificate presented by the server. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary code in the context of root. Was ZDI-CAN-12362.

NVD Source

Technical Analysis

CVE-2021-27257 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 full integrity compromise (data manipulation), with a CVSS base score of 6.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorAdjacent
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected Vendors & Products

netgear86 product(s)
br200 firmwarebr200br500 firmwarebr500d7800 firmwared7800ex6100v2 firmwareex6100v2ex6150v2 firmwareex6150v2ex6250 firmwareex6250+74
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-21-264/
ADVISORYhttps://www.zerodayinitiative.com/advisories/ZDI-21-264/

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-21-264/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-21-264/Third Party Advisory · VDB Entry

Quick Facts

CVE IDCVE-2021-27257
CVSS Score6.5 / 10
SeverityMEDIUM
WeaknessCWE-295
CISA KEVNo
Affected1 vendor(s)
PublishedMar 5, 2021

Related CVEs (CWE-295)

CVE-2026-4370
10.0
CVE-2018-9127
9.8
CVE-2025-35434
9.8
CVE-2015-2320
9.8
CVE-2010-1378
9.8
CVE-2018-4991
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-27257 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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