HOMEVULNERABILITIESCVE-2021-20859
HIGH

CVE-2021-20859

CWE-78Published: December 1, 2021· Updated: Jun 17, 2026

8.0
CVSS v3.1

Official Description

ELECOM LAN routers (WRC-1167GST2 firmware v1.25 and prior, WRC-1167GST2A firmware v1.25 and prior, WRC-1167GST2H firmware v1.25 and prior, WRC-2533GS2-B firmware v1.52 and prior, WRC-2533GS2-W firmware v1.52 and prior, WRC-1750GS firmware v1.03 and prior, WRC-1750GSV firmware v2.11 and prior, WRC-1900GST firmware v1.03 and prior, WRC-2533GST firmware v1.03 and prior, WRC-2533GSTA firmware v1.03 and prior, WRC-2533GST2 firmware v1.25 and prior, WRC-2533GST2SP firmware v1.25 and prior, WRC-2533GST2-G firmware v1.25 and prior, and EDWRC-2533GST2 firmware v1.25 and prior) allows a network-adjacent authenticated attacker to execute an arbitrary OS command via unspecified vectors.

NVD Source

Technical Analysis

CVE-2021-20859 requires adjacent network access, limiting remote exploitation but still posing risk in shared or local network environments.

Exploitation requires low 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 8.0.

CVSS v3.1 Vector Breakdown

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

Affected Vendors & Products

elecom28 product(s)
wrc-1167gst2 firmwarewrc-1167gst2wrc-1167gst2a firmwarewrc-1167gst2awrc-1167gst2h firmwarewrc-1167gst2hwrc-2533gs2-b firmwarewrc-2533gs2-bwrc-2533gs2-w firmwarewrc-2533gs2-wwrc-1750gs firmwarewrc-1750gs+16
Source: NVD CPE · 28 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-2021-20859
CVSS Score8.0 / 10
SeverityHIGH
WeaknessCWE-78
CISA KEVNo
Affected1 vendor(s)
PublishedDec 1, 2021

Related CVEs (CWE-78)

CVE-2008-6554
10.0
CVE-2013-5486
10.0
CVE-2008-4796
10.0
CVE-2008-4304
10.0
CVE-2010-0418
10.0
CVE-2010-2445
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-20859 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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