{"id":"CVE-2026-107838","revision":"240a7e3240ee4d4396521e066ed69b97","records":[{"revision":"240a7e3240ee4d4396521e066ed69b97","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-107838","aliases":[],"title":"RIOT: nanocoap_fileserver ignores response initialization failure, leading to reachable assertion","description":"RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. From version 2023.07 through version 2026.07, nanocoap_fileserver callers in sys/net/application_layer/nanocoap/fileserver.c ignore a failure returned by _resp_init() when coap_build_reply() cannot fit a response header into the response buffer. A remote client can send a CoAP request with a sufficiently large extended token when nanocoap_token_ext is enabled, causing response initialization to fail while _get_file() or _get_directory() continues with stale response state. The path then reaches _calc_szx2() and its pdu->payload_len > reserve assertion, terminating the affected service or device task. No fixed release is available as of this review.","state":0,"publishedAt":"2026-10-09T17:55:34.67+00:00","modifiedAt":"2026-10-13T17:07:38.7+00:00","affected":[{"ecosystem":"Vendor product","name":"RIOT","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"RIOT-OS\",\n                    \"product\": \"RIOT\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 2023.07, <= 2026.07\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-39j3-3v73-5mj2","https://github.com/RIOT-OS/RIOT/pull/22745","https://github.com/RIOT-OS/RIOT/commit/d3a47289c58d108575a19e623e4d3f647659e743"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-107838","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-107838","identifiers":["CVE-2026-107838"]},"retained":false,"historicalAffected":[]}],"coverage":[]}