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CVE-2021-43083

28
FAUCET Score

CVE-2021-43083 is an unsigned integer underflow vulnerability affecting the C language implementation of Apache PLC4X (PLC4C) in its TCP transport. This flaw carries a high CVSS score of 8.8, indicating a severe impact on confidentiality, integrity, and availability, though it requires a user to connect to a malicious device. Despite its high severity, there is currently no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed on the KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.9.1CPE matchmatch criteria
cpe:2.3:a:apache:plc4x:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.92%
Probability of exploitation in next 30 days
EPSS Percentile
77.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0192 is in the 76th percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

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

lists.apache.org / thread/jxx6qc84z60xbbhn6vp2s5qf09psrtc7
Vendor Advisory
openwall.com / lists/oss-security/2021/12/20/2
Mailing ListThird Party Advisory