CVE-2021-42146Network attack vector

Sensitive-data disclosure via DTLS epoch reuse

Published Jan 24, 2024 · Updated Jun 20, 2025

Information disclosure in Contiki-NG tinyDTLS 53a0d97 and earlier allows remote attackers to read connected clients' application data. The DTLS server handshake handling accepts reuse of the same epoch number within twice the TCP maximum segment lifetime instead of rejecting it. No authentication or user interaction is required, and successful exploitation exposes sensitive application data belonging to connected clients.

CVSS severity7.5
High
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Contiki-NG tinyDTLS 53a0d97 and earlier allows remote attackers to read connected clients' application data. The DTLS server handshake handling accepts reuse of the same epoch number within twice the TCP maximum segment lifetime instead of rejecting it. No authentication or user interaction is required, and successful exploitation exposes sensitive application data belonging to connected clients.

The record

CVE
CVE-2021-42146
Published
Jan 24, 2024
Updated
Jun 20, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-303, CWE-755
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:H/I:N/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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-303Incorrect Implementation of Authentication Algorithm
CWE-755Improper Handling of Exceptional Conditions

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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