HOMEVULNERABILITIESCVE-2021-39510
CRITICAL

CVE-2021-39510

CWE-77Published: August 24, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

An issue was discovered in D-Link DIR816_A1_FW101CNB04 750m11ac wireless router, The HTTP request parameter is used in the handler function of /goform/form2userconfig.cgi route, which can construct the user name string to delete the user function. This can lead to command injection through shell metacharacters.

NVD Source

Technical Analysis

CVE-2021-39510 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

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 9.8.

CVSS v3.1 Vector Breakdown

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

Affected Vendors & Products

dlink2 product(s)
dir-816 firmwaredir-816
Source: NVD CPE · 2 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://github.com/doudoudedi/main-DIR-816_A1_Command-injection
ADVISORYhttps://github.com/doudoudedi/main-DIR-816_A1_Command-injection/blob/main/injection_A1.md
ADVISORYhttps://www.dlink.com/en/security-bulletin/
ADVISORYhttps://github.com/doudoudedi/main-DIR-816_A1_Command-injection
ADVISORYhttps://github.com/doudoudedi/main-DIR-816_A1_Command-injection/blob/main/injection_A1.md
ADVISORYhttps://www.dlink.com/en/security-bulletin/

All References (6)

→
https://github.com/doudoudedi/main-DIR-816_A1_Command-injectionThird Party Advisory
→
https://github.com/doudoudedi/main-DIR-816_A1_Command-injection/blob/main/injection_A1.mdExploit · Third Party Advisory
→
https://www.dlink.com/en/security-bulletin/Vendor Advisory
→
https://github.com/doudoudedi/main-DIR-816_A1_Command-injectionThird Party Advisory
→
https://github.com/doudoudedi/main-DIR-816_A1_Command-injection/blob/main/injection_A1.mdExploit · Third Party Advisory
→
https://www.dlink.com/en/security-bulletin/Vendor Advisory

Quick Facts

CVE IDCVE-2021-39510
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-77
CISA KEVNo
Affected1 vendor(s)
PublishedAug 24, 2021

Related CVEs (CWE-77)

CVE-2015-1949
10.0
CVE-2015-1986
10.0
CVE-2024-20418
10.0
CVE-2015-1938
10.0
CVE-2024-32766
10.0
CVE-2017-7876
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-39510 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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