CVE-2026-5855Network attack vector

Service interruption via unchecked TLV buffer length

Published Aug 6, 2026 · Updated Aug 6, 2026

Out-of-bounds read in Contiki-NG allows remote attackers to interrupt LwM2M processing via a crafted CoAP WRITE to an endpoint. lwm2m_tlv_read() ignores the supplied buffer length, reads a truncated TLV header beyond the input, and derives an invalid parse offset from adjacent heap data. NoSec mode requires no authentication; the record does not identify whether interruption occurs through a hang, crash, or another failure mode.

CVSS severity8.7
High
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Contiki-NG allows remote attackers to interrupt LwM2M processing via a crafted CoAP WRITE to an endpoint. lwm2m_tlv_read() ignores the supplied buffer length, reads a truncated TLV header beyond the input, and derives an invalid parse offset from adjacent heap data. NoSec mode requires no authentication; the record does not identify whether interruption occurs through a hang, crash, or another failure mode.

The record

CVE
CVE-2026-5855
Published
Aug 6, 2026
Updated
Aug 6, 2026
Vendor
Contiki-NG
Product
Contiki-NG
Classifications
CWE-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 2026Record 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=0 <f1673b5766d4d4d514cefb8a0350f43653574997

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Contiki-NG · Contiki-NGversion=0 <f1673b5766d4d4d514cefb8a0350f43653574997

Published CVSS scores

7.5VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-125Out-of-bounds Read
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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