What is the CVSS score of CVE-2026-27703?

CVE-2026-27703 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N. EPSS exploitation probability: 0.0%.

Which versions of IoT are affected by CVE-2026-27703?

A HIGH severity vulnerability (CVE-2026-27703) affects RIOT, an open-source IoT microcontroller operating system, with no patch currently available.

How to fix or mitigate CVE-2026-27703?

Within 24 hours: Inventory all RIOT-based devices and systems in your environment and assess exposure scope. Within 7 days: Implement network segmentation to isolate affected IoT/embedded devices from critical systems; disable unnecessary network services on RIOT devices where operationally feasible. Within 30 days: Establish continuous monitoring for exploitation attempts; contact RIOT project maintainers for patch timelines; evaluate replacement or upgrade paths to patched versions as they become available.

IoT CVE-2026-27703

HIGH

Out-of-bounds Write (CWE-787)

2026-03-11 security-advisories@github.com

IoT Denial Of Service

7.5

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 22:07 vuln.today

CVE Published

Mar 11, 2026 - 20:16 nvd

HIGH 7.5

DescriptionGitHub Advisory

RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. In 2026.01 and earlier, the default handler for the well_known_core resource coap_well_known_core_default_handler writes user-provided option data and other data into a fixed size buffer without validating the buffer is large enough to contain the response. This vulnerability allows an attacker to corrupt neighboring stack location, including security-sensitive addresses like the return address, leading to denial of service or arbitrary code execution.

AnalysisAI

Stack buffer overflow in RIOT OS coap_well_known_core_default_handler allows unauthenticated remote attackers to overwrite critical stack data including return addresses through oversized CoAP option responses. Affected IoT devices running RIOT 2026.01 and earlier are vulnerable to denial of service or arbitrary code execution without any user interaction required. No patch is currently available for this vulnerability.

Technical ContextAI

Classified as CWE-787 (Out-of-bounds Write). RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. In 2026.01 and earlier, the default handler for the well_known_core resource coap_well_known_core_default_handler writes user-provided option data and other data into a fixed size buffer without validating the buffer is large enough to contain the response. This vulnerability allows an attacker to corrupt neighboring stack location, including

Affected ProductsAI

RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded dev

RemediationAI

Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible. Restrict network access to the affected service where possible.