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CVE-2026-5855— Contiki-NG LwM2M TLV Parser Out-of-Bounds Read via Unchecked Buffer Length in lwm2m_tlv_read

Quick assessment

Affected
Contiki-NG Contiki-NG
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Contiki-NG是Contiki-NG组织开源的一个适用于物联网中资源受限设备的操作系统。 Contiki-NG 存在缓冲区错误漏洞，该漏洞源于LwM2M TLV解析器lwm2m_tlv_read()忽略调用者提供的缓冲区长度参数且无边界检查，可能导致越界读取堆内存，泄露内存内容（包括密钥材料和对端地址），并破坏解析偏移。在LwM2M NoSec模式下，攻击者无需认证即可触发。

CVSS 7.5 · High EPSS 0.54% · P43

Affected Version Matrix 1

VendorProduct Version RangeStatus
Contiki-NG Contiki-NG < f1673b5766d4d4d514cefb8a0350f43653574997 affected
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I. Basic Information for CVE-2026-5855

Vulnerability Information
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Vulnerability Title
Contiki-NG LwM2M TLV Parser Out-of-Bounds Read via Unchecked Buffer Length in lwm2m_tlv_read
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5
Vulnerability Title
Contiki-NG 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Contiki-NG是Contiki-NG组织开源的一个适用于物联网中资源受限设备的操作系统。 Contiki-NG 存在缓冲区错误漏洞，该漏洞源于LwM2M TLV解析器lwm2m_tlv_read()忽略调用者提供的缓冲区长度参数且无边界检查，可能导致越界读取堆内存，泄露内存内容（包括密钥材料和对端地址），并破坏解析偏移。在LwM2M NoSec模式下，攻击者无需认证即可触发。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Contiki-NG Contiki-NG 0 ~ f1673b5766d4d4d514cefb8a0350f43653574997 -

II. Public POCs for CVE-2026-5855

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 11253 chars
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III. Intelligence Information for CVE-2026-5855

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Patches & Fixes for CVE-2026-5855 (2)

Vendor Pages for CVE-2026-5855 (1)

Same Patch Batch · Contiki-NG · 2026-08-06 · 3 CVEs total

CVE-2026-5857 8.1 HIGH Contiki-NG MQTT Client Out-of-Bounds Write in PUBLISH Topic Parser via Persistent State Be
CVE-2026-5856 7.1 HIGH Contiki-NG DNS/mDNS Resolver Out-of-Bounds Read via Unchecked skip_name Traversal Before T

IV. Related Vulnerabilities

Same product: Contiki-NG
Same vendor: Contiki-NG
Same weakness: CWE-125

V. Comments for CVE-2026-5855

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