{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-107836",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-10-08T22:34:49.289Z",
        "datePublished": "2026-10-09T17:49:41.120Z",
        "dateUpdated": "2026-10-09T18:00:37.637Z"
    },
    "containers": {
        "cna": {
            "title": "RIOT: nanoCoAP Block2 client slice handling underflows on inconsistent server-controlled block size",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-125",
                            "lang": "en",
                            "description": "CWE-125: Out-of-bounds Read",
                            "type": "CWE"
                        }
                    ]
                },
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-191",
                            "lang": "en",
                            "description": "CWE-191: Integer Underflow (Wrap or Wraparound)",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "privilegesRequired": "NONE",
                        "userInteraction": "PASSIVE",
                        "vulnConfidentialityImpact": "LOW",
                        "vulnIntegrityImpact": "NONE",
                        "vulnAvailabilityImpact": "HIGH",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "baseScore": 7.1,
                        "baseSeverity": "HIGH",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N",
                        "version": "4.0"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-x924-p5fq-26pc",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-x924-p5fq-26pc"
                },
                {
                    "name": "https://github.com/RIOT-OS/RIOT/pull/22518",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/RIOT-OS/RIOT/pull/22518"
                },
                {
                    "name": "https://github.com/RIOT-OS/RIOT/commit/49b894cbe091510093273b98d92c4a17167d6839",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/RIOT-OS/RIOT/commit/49b894cbe091510093273b98d92c4a17167d6839"
                }
            ],
            "affected": [
                {
                    "vendor": "RIOT-OS",
                    "product": "RIOT",
                    "versions": [
                        {
                            "version": "<= 2026.07",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-10-09T17:49:41.120Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. In 2026.07 and earlier, the nanoCoAP client function nanocoap_sock_get_slice() in sys/net/application_layer/nanocoap/sock.c accepts a Block2 response when _block_cb() sees the expected block number without also verifying that the server-controlled szx and derived offset match the requested block geometry. A malicious CoAP server can return the expected block number with a larger block size, causing the derived offset to exceed the client slice offset and making ctx->offset - offset underflow in _2buf_slice(). The resulting buffer-relative calculation can read before the payload buffer and crash the client, causing denial of service and potentially exposing adjacent memory. No fixed release is available as of this review."
                }
            ],
            "source": {
                "advisory": "GHSA-x924-p5fq-26pc",
                "discovery": "UNKNOWN"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-10-09T17:59:40.461358Z",
                                "id": "CVE-2026-107836",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-10-09T18:00:37.637Z"
                }
            }
        ]
    }
}