CVE-2026-27703Public exploitNetwork attack vector

Code execution via unchecked CoAP response pointer

Published Mar 11, 2026 · Updated Mar 11, 2026

Out-of-bounds write in RIOT 2026.01 and earlier allows remote attackers to corrupt stack memory through a crafted CoAP request. coap_well_known_core_default_handler derives a response payload pointer from an extended token length, then writes through it without checking the fixed buffer boundary. Exploitation requires an exposed nanoCoAP server with the well-known/core resource and extended tokens enabled; corruption can interrupt the service or hijack execution.

CVSS severity7.5
High
EPSS probability0.48%
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 write in RIOT 2026.01 and earlier allows remote attackers to corrupt stack memory through a crafted CoAP request. coap_well_known_core_default_handler derives a response payload pointer from an extended token length, then writes through it without checking the fixed buffer boundary. Exploitation requires an exposed nanoCoAP server with the well-known/core resource and extended tokens enabled; corruption can interrupt the service or hijack execution.

The record

CVE
CVE-2026-27703
Published
Mar 11, 2026
Updated
Mar 11, 2026
Vendor
RIOT-OS
Product
RIOT
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 11, 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=<= 2026.01

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

RIOT-OS · RIOTversion=<= 2026.01

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

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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