How severe is CVE-2021-34433?

CVE-2021-34433 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-34433 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34433?

CVE-2021-34433 primarily affects Eclipse Californium. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34433?

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-2021-34433 published?

CVE-2021-34433 was published on 2021-08-20 and last updated on 2026-06-17.

CVE-2021-34433

CVE-2021-34433 is a high-severity vulnerability in Eclipse Californium with a CVSS 3.x base score of 7.5. 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-347.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 0% (26th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-347
Affected product: Eclipse Californium
Published: 2021-08-20
Last modified: 2026-06-17

Description

In Eclipse Californium version 2.0.0 to 2.6.4 and 3.0.0-M1 to 3.0.0-M3, the certificate based (x509 and RPK) DTLS handshakes accidentally succeeds without verifying the server side's signature on the client side, if that signature is not included in the server's ServerKeyExchange.

Frequently asked questions

What is CVE-2021-34433?: In Eclipse Californium version 2.0.0 to 2.6.4 and 3.0.0-M1 to 3.0.0-M3, the certificate based (x509 and RPK) DTLS handshakes accidentally succeeds without verifying the server side's signature on the client side, if that signature is not included in the server's ServerKeyExchange.
How severe is CVE-2021-34433?: CVE-2021-34433 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-34433 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34433?: CVE-2021-34433 primarily affects Eclipse Californium. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34433?: 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-2021-34433 published?: CVE-2021-34433 was published on 2021-08-20 and last updated on 2026-06-17.

References

https://bugs.eclipse.org/bugs/show_bug.cgi?id=575281

Affected products (4)

cpe:2.3:a:eclipse:californium:*:*:*:*:*:*:*:*
cpe:2.3:a:eclipse:californium:3.0.0:m1:*:*:*:*:*:*
cpe:2.3:a:eclipse:californium:3.0.0:m2:*:*:*:*:*:*
cpe:2.3:a:eclipse:californium:3.0.0:m3:*:*:*:*:*:*

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