CVE-2026-5855 (GCVE-0-2026-5855)

Vulnerability from cvelistv5 – Published: 2026-08-06 18:39 – Updated: 2026-08-14 16:50
VLAI
Title
Contiki-NG LwM2M TLV Parser Out-of-Bounds Read via Unchecked Buffer Length in lwm2m_tlv_read
Summary
Contiki-NG's LwM2M TLV parser lwm2m_tlv_read() in os/services/lwm2m/lwm2m-tlv.c ignores its caller-supplied buffer length argument and reads up to six bytes from the input buffer with no bounds check. The caller in lwm2m-engine.c iterates while there is at least one byte remaining, so a crafted CoAP WRITE to any LwM2M endpoint whose final TLV supplies exactly one byte triggers up to five out-of-bounds reads of heap memory adjacent to the CoAP input buffer, disclosing memory contents (including key material and peer addresses) through the parsed tlv->id, tlv->length, and tlv->value fields. Corrupted tlv_len derived from the out-of-bounds memory further corrupts the caller's parse offset. In LwM2M NoSec mode, the default for constrained devices, no authentication is required.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-07 16:19 UTC
CWE
Assigner
VulnCheck CNA under the mitre root
CNA scorecard B 84/100 over 6373 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Contiki-NG Contiki-NG Affected: 0 , < f1673b5766d4d4d514cefb8a0350f43653574997 (custom)
    cpe:2.3:o:contiki-ng:contiki-ng:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-08-06 19:00
Credits
Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc.
Show details on NVD website
To clipboard 

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}



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