{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "last_affected": "2026.01"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "c699e2e20a6c2d0fd45daa766d7a192cb33e579f"
            }
          ],
          "repo": "https://github.com/riot-os/riot",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-qgj4-9jff-93cj"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-787"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27703.json"
  },
  "details": "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.",
  "id": "CVE-2026-27703",
  "modified": "2026-08-12T03:51:36.884818566Z",
  "published": "2026-03-11T19:38:02.866Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27703.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-qgj4-9jff-93cj"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27703"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "RIOT has an Out-of-Bounds Write in nanoCoAP Handler"
}