HOMEVULNERABILITIESCVE-2021-20852
MEDIUM

CVE-2021-20852

CWE-120Published: December 1, 2021· Updated: Jun 17, 2026

6.8
CVSS v3.1

Official Description

Buffer overflow vulnerability in ELECOM LAN routers (WRH-733GBK firmware v1.02.9 and prior and WRH-733GWH firmware v1.02.9 and prior) allows a network-adjacent attacker with an administrator privilege to execute an arbitrary OS command via unspecified vectors.

NVD Source

Technical Analysis

CVE-2021-20852 requires adjacent network access, limiting remote exploitation but still posing risk in shared or local network environments.

Exploitation requires high privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

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 6.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorAdjacent
Attack ComplexityLow
Privileges Req.High
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

elecom4 product(s)
wrh-733gbk firmwarewrh-733gbkwrh-733gwh firmwarewrh-733gwh
Source: NVD CPE · 4 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

ADVISORYhttps://jvn.jp/en/jp/JVN88993473/index.html
ADVISORYhttps://www.elecom.co.jp/news/security/20211130-01/
ADVISORYhttps://jvn.jp/en/jp/JVN88993473/index.html
ADVISORYhttps://www.elecom.co.jp/news/security/20211130-01/

All References (4)

→
https://jvn.jp/en/jp/JVN88993473/index.htmlThird Party Advisory
→
https://www.elecom.co.jp/news/security/20211130-01/Vendor Advisory
→
https://jvn.jp/en/jp/JVN88993473/index.htmlThird Party Advisory
→
https://www.elecom.co.jp/news/security/20211130-01/Vendor Advisory

Quick Facts

CVE IDCVE-2021-20852
CVSS Score6.8 / 10
SeverityMEDIUM
WeaknessCWE-120
CISA KEVNo
Affected1 vendor(s)
PublishedDec 1, 2021

Related CVEs (CWE-120)

CVE-2022-22570
10.0
CVE-2025-9962
10.0
CVE-2007-1770
10.0
CVE-2012-10035
10.0
CVE-2002-1337
10.0
CVE-2026-24800
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-20852 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. CVE data is provided under the NVD usage policy.
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