{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-107838",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-10-08T22:34:49.290Z",
        "datePublished": "2026-10-09T17:55:34.670Z",
        "dateUpdated": "2026-10-09T17:55:34.670Z"
    },
    "containers": {
        "cna": {
            "title": "RIOT: nanocoap_fileserver ignores response initialization failure, leading to reachable assertion",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-252",
                            "lang": "en",
                            "description": "CWE-252: Unchecked Return Value",
                            "type": "CWE"
                        }
                    ]
                },
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-617",
                            "lang": "en",
                            "description": "CWE-617: Reachable Assertion",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "attackComplexity": "LOW",
                        "attackVector": "NETWORK",
                        "availabilityImpact": "HIGH",
                        "baseScore": 7.5,
                        "baseSeverity": "HIGH",
                        "confidentialityImpact": "NONE",
                        "integrityImpact": "NONE",
                        "privilegesRequired": "NONE",
                        "scope": "UNCHANGED",
                        "userInteraction": "NONE",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                        "version": "3.1"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-39j3-3v73-5mj2",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-39j3-3v73-5mj2"
                },
                {
                    "name": "https://github.com/RIOT-OS/RIOT/pull/22745",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/RIOT-OS/RIOT/pull/22745"
                },
                {
                    "name": "https://github.com/RIOT-OS/RIOT/commit/d3a47289c58d108575a19e623e4d3f647659e743",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/RIOT-OS/RIOT/commit/d3a47289c58d108575a19e623e4d3f647659e743"
                }
            ],
            "affected": [
                {
                    "vendor": "RIOT-OS",
                    "product": "RIOT",
                    "versions": [
                        {
                            "version": ">= 2023.07, <= 2026.07",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-10-09T17:55:34.670Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "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."
                }
            ],
            "source": {
                "advisory": "GHSA-39j3-3v73-5mj2",
                "discovery": "UNKNOWN"
            }
        }
    }
}