{"uuid": "be78d075-26db-4a5a-9ca8-c61f5441de9f", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-107838", "type": "seen", "source": "https://infosec.exchange/users/cve/statuses/117412266635635576", "content": "CVE-2026-107838 RIOT: nanocoap_fileserver ignores response initialization failure, leading to reachable assertion 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.\nhttps://www.cve.org/CVERecord?id=CVE-2026-107838https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-39j3-3v73-5mj2https://github.com/RIOT-OS/RIOT/pull/22745https://github.com/RIOT-OS/RIOT/commit/d3a47289c58d108575a19e623e4d3f647659e743#RIOT-OS #RIOT#CVE_2026_107838#bot", "creation_timestamp": "2026-10-09T18:03:30.495756Z"}