CVE-2026-27703: high-severity vulnerability in RIOT-OS RIOT
RIOT has an Out-of-Bounds Write in nanoCoAP Handler
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.5%
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:N/I:H/A:N
Affected products
RIOT-OS · RIOTRelated CVEs — RIOT-OS RIOT
In the same product, most dangerous first.
CVE-2024-32017CRITICALBuffer overflows in RIOTEPSS 1.6%CVE-2024-32018HIGHIneffective size check due to assert() and buffer overflow in RIOTEPSS 1.5%CVE-2023-33975CRITICALRIOT-OS vulnerable to Out of Bounds Write in _rbuf_addEPSS 1.5%CVE-2024-31225HIGHLack of size check and buffer overflow in RIOTEPSS 1.3%CVE-2023-24818HIGHRIOT-OS vulnerable to null pointer dereference during fragment forwardingEPSS 1.2%CVE-2023-24823CRITICALRIOT-OS vulnerable to Packet Type Confusion during IPHC sendEPSS 1.0%