{"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"}}]}}

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{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,2026.07]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "RIOT", "source": "cna", "vendor": "RIOT-OS"}, "product": "riot", "vendor": "riot-os"}], "created": "2026-10-09T19:30:10.844623+00:00", "updated": "2026-10-09T19:30:10.844652+00:00", "vendors": ["riot-os", "riot-os$PRODUCT$riot"]}