← Vulnerability feed

Vulnerability record · CVE-2026-27703 · published 11 March 2026

CVE-2026-27703: Riot-os riot out-of-bounds write vulnerability

Riot Os · Riot

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.

9.8 CVSS 3.1 Critical EPSS 0.60% · top 53.5% CWE-787 · Out-of-bounds write
9.8CVSS 3.1 base score
0.60%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References, 1 tagged exploit
17 Jun 2026Last modified by NVD

Description

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-qgj4-9jff-93cj ExploitVendor Advisory

Track CVE-2026-27703 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2023-33975Riot-os riot memory buffer overflow vulnerabilityRIOT-OS, an operating system for Internet of Things (IoT) devices, contains a network stack with the ability to process 6LoWPAN frames. In version 20…EPSS 1.5%9.8CVE-2023-24823Riot-os riot out-of-bounds write vulnerabilityRIOT-OS, an operating system that supports Internet of Things devices, contains a network stack with the ability to process 6LoWPAN frames. Prior to …EPSS 0.99%9.8CVE-2023-24819Riot-os riot out-of-bounds write vulnerabilityRIOT-OS, an operating system that supports Internet of Things devices, contains a network stack with the ability to process 6LoWPAN frames. Prior to …EPSS 0.99%9.8CVE-2021-27427Riot-os riot integer overflow vulnerabilityRIOT OS version 2020.01.1 is vulnerable to integer wrap-around in its implementation of calloc function, which can lead to arbitrary memory allocatio…EPSS 1.7%9.8CVE-2021-27357Riot-os riot classic buffer overflow vulnerabilityRIOT-OS 2020.01 contains a buffer overflow vulnerability in /sys/net/gnrc/routing/rpl/gnrc_rpl_control_messages.c.EPSS 1.2%9.8CVE-2021-27697Riot-os riot classic buffer overflow vulnerabilityRIOT-OS 2021.01 contains a buffer overflow vulnerability in sys/net/gnrc/routing/rpl/gnrc_rpl_validation.c through the gnrc_rpl_validation_options() …EPSS 1.3%9.8CVE-2021-27698Riot-os riot classic buffer overflow vulnerabilityRIOT-OS 2021.01 contains a buffer overflow vulnerability in /sys/net/gnrc/routing/rpl/gnrc_rpl_control_messages.c through the _parse_options() functi…EPSS 1.2%9.8CVE-2020-15350Riot-os riot memory buffer overflow vulnerabilityRIOT 2020.04 has a buffer overflow in the base64 decoder. The decoding function base64_decode() uses an output buffer estimation function to compute …EPSS 1.5%

Source: NIST National Vulnerability Database (record CVE-2026-27703), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.