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CVE-2021-21816

46
FAUCET Score

CVE-2021-21816 is an information disclosure vulnerability in the Syslog functionality of D-Link DIR-3040 1.13B03 routers. An attacker can trigger this vulnerability by sending a specially crafted HTTP request, leading to the disclosure of sensitive information. With a CVSS score of 4.3 (Medium), the attack requires no privileges and has low complexity, but relies on user interaction (UI:R) for successful exploitation. While not listed on the KEV catalog, its high EPSS and FAUCET Risk Scores, along with the availability of Nuclei templates, indicate a significant potential for exploitation. Community discussion and media coverage further highlight the attention this vulnerability has received.

Impacted Technologies

VendorProductVersion(s)CPE
1.13b03CPE matchmatch criteria
cpe:2.3:o:dlink:dir-3040_firmware:1.13b03:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

6.5MEDIUM

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
36.49%
Probability of exploitation in next 30 days
EPSS Percentile
98.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Nuclei: CVE-2021-21816 · Aug 1, 2021
This CVE's current EPSS score of 0.3649 is in the 99th percentile among its peer group of 26,234 CVEs.

Social Chatter

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

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

talosintelligence.com / vulnerability_reports/TALOS-2021-1281
ExploitThird Party Advisory