CVE-2021-42145Network attack vector

DTLS server crash via cipher-state assertion

Published Jan 24, 2024 · Updated Jun 20, 2025

Improper exception handling in Contiki-NG tinyDTLS through 2018-08-30 allows remote attackers to crash a DTLS server. The check_certificate_request() function asserts that the peer cipher is TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 instead of rejecting a CertificateRequest received in an inconsistent handshake state, causing abort() to terminate the process. No authentication or user interaction is required; the bounded impact is interruption of the affected DTLS service through process termination.

CVSS severity7.5
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in Contiki-NG tinyDTLS through 2018-08-30 allows remote attackers to crash a DTLS server. The check_certificate_request() function asserts that the peer cipher is TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 instead of rejecting a CertificateRequest received in an inconsistent handshake state, causing abort() to terminate the process. No authentication or user interaction is required; the bounded impact is interruption of the affected DTLS service through process termination.

The record

CVE
CVE-2021-42145
Published
Jan 24, 2024
Updated
Jun 20, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-755, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 24, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 20, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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