How severe is CVE-2021-43083?

CVE-2021-43083 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-43083 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43083?

CVE-2021-43083 affects Apache Plc4x. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-43083?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-43083 published?

CVE-2021-43083 was published on 2021-12-19 and last updated on 2026-06-17.

CVE-2021-43083

CVE-2021-43083 is a high-severity vulnerability in Apache Plc4x with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-191.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-191
Affected product: Apache Plc4x
Published: 2021-12-19
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-43083?: 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.
How severe is CVE-2021-43083?: CVE-2021-43083 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-43083 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43083?: CVE-2021-43083 affects Apache Plc4x. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-43083?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-43083 published?: CVE-2021-43083 was published on 2021-12-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:plc4x:*:*:*:*:*:*:*:*

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