Buffer overflow in Riot-Os Riot
CVE-2026-27703
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.006 (46.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
- Riot-Os Riot — versions <= 2026.01
Weakness classification (CWE)
References
- github.com/RIOT-OS/RIOT/security/advisories/GHSA-qgj4-9jff-93cj (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-27703?
- CVE-2026-27703 is a high-severity vulnerability in Riot-Os Riot, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2026-03-11.
- How severe is CVE-2026-27703?
- High severity. CVSS v3 base score is 7.5 out of 10.