CVE-2020-13602Network attack vector

Device hang via unsupported LwM2M TLV type

Published May 24, 2021 · Updated Sep 17, 2024

An infinite loop in Zephyr RTOS 1.14.2 and 2.2.0 allows remote attackers who can inject LwM2M messages to hang the device. In do_write_op_tlv, an unsupported TLV type receives no processing or error return, so the parser loop never advances or exits. Exploitation requires access to the privileged LwM2M protocol, which is not expected to be exposed to the internet, and interrupts device service.

CVSS severity5.5
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An infinite loop in Zephyr RTOS 1.14.2 and 2.2.0 allows remote attackers who can inject LwM2M messages to hang the device. In do_write_op_tlv, an unsupported TLV type receives no processing or error return, so the parser loop never advances or exits. Exploitation requires access to the privileged LwM2M protocol, which is not expected to be exposed to the internet, and interrupts device service.

The record

CVE
CVE-2020-13602
Published
May 24, 2021
Updated
Sep 17, 2024
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-20, CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.14.2 <unspecified
  2. Affected versionversion=2.2.0 <unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=1.14.2 <unspecified; version=2.2.0 <unspecified

Published CVSS scores

2.1NVDAV:L/AC:L/Au:N/C:N/I:N/A:P
5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0Zephyr ProjectCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
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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