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CVE-2021-43722

31
FAUCET Score

CVE-2021-43722 is a critical buffer overflow vulnerability affecting D-Link DIR-645 1.03 A1 routers, specifically within the hnap_main function's cgibin handler due to unbounded sprintf usage on the soapaction header. With a CVSS score of 9.8, this vulnerability allows for unauthenticated, remote exploitation with high impact on confidentiality, integrity, and availability. Despite its severity, there is no public exploit code available (Metasploit, Nuclei, ExploitDB), it is not listed in CISA's KEV catalog, and there is no community discussion or media coverage indicating active exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
1.03CPE matchmatch criteria
cpe:2.3:o:dlink:dir-645_firmware:1.03:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.11%
Probability of exploitation in next 30 days
EPSS Percentile
86.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0311 is in the 78th percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

github.com / luqiut/iot/blob/main/DIR-645%20Stack%20overflow.md
ExploitThird Party Advisory
dlink.com / en/security-bulletin
Vendor Advisory