CVE-2021-43083

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.8 under NVD CVSS v3. EPSS exploit probability: 1.9%, top 22% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
8.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 2%CVSS: 8.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Apache PLC4X - PLC4C (Only the C language implementation was effected) was vulnerable to an unsigned integer underflow flaw inside the tcp transport. Users should update to 0.9.1, which addresses this issue. However, in order to exploit this vulnerability, a user would have to actively connect to a mallicious device which could send a response with invalid content. Currently we consider the probability of this being exploited as quite minimal, however this could change in the future, especially with the industrial networks growing more and more together.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
45(Track)
EG Risk 45/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity88% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
77.8%
KEV
Not listed

Published

December 19, 2021

Last Modified

November 21, 2024

References (4)

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 103 total refreshes for this CVE.

  1. 2026-07-23 02:05 UTCEG score recompute
  2. 2026-07-22 22:51 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2021-43083?
CVE-2021-43083 is a high vulnerability published on December 19, 2021. Apache PLC4X - PLC4C (Only the C language implementation was effected) was vulnerable to an unsigned integer underflow flaw inside the tcp transport. Users should update to 0.9.1, which addresses this issue. However, in order to exploit this vulnerability, a user would have to actively connect to a…
When was CVE-2021-43083 disclosed?
CVE-2021-43083 was first published in the National Vulnerability Database on December 19, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-43083 actively exploited?
CVE-2021-43083 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 77.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-43083?
CVE-2021-43083 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2021-43083?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-43083, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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