{"id":"CVE-2026-107836","revision":null,"records":[{"revision":"a4099cdff1c2442b91505521179e295c","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-107836","aliases":[],"title":"RIOT: nanoCoAP Block2 client slice handling underflows on inconsistent server-controlled block size","description":"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.","state":0,"publishedAt":"2026-10-09T17:49:41.12+00:00","modifiedAt":"2026-10-09T18:00:37.637+00:00","affected":[{"ecosystem":"Vendor product","name":"RIOT","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"RIOT-OS\",\n                    \"product\": \"RIOT\",\n                    \"versions\": [\n                        {\n                            \"version\": \"<= 2026.07\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"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","score":7.1,"severity":"HIGH"}],"references":["https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-x924-p5fq-26pc","https://github.com/RIOT-OS/RIOT/pull/22518","https://github.com/RIOT-OS/RIOT/commit/49b894cbe091510093273b98d92c4a17167d6839"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-107836","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-107836","identifiers":["CVE-2026-107836"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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Not a global EPSS backfill.","generation":"2026-11-10T13:22:12.0568802+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-10T13:22:12.0568802+00:00","lastSuccessAt":"2026-11-10T13:22:12.2192335+00:00","error":null,"lastVerifiedAt":"2026-11-10T13:22:12.219234+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-fce56865ab584da18fe65ffedaec05f5","complete":false,"records":13697,"lastAttemptAt":"2026-11-10T13:22:38.4294414+00:00","lastSuccessAt":"2026-11-10T13:22:38.423+00:00","error":"100 identifier lookups failed; latest failures include request timeout. Other identifiers were checked independently.","lastVerifiedAt":"2026-11-10T13:22:38.423+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13642,"expectedIdentifiers":13744,"failedIdentifiers":100},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-cdffb4589856378aa42e8d1bd4a6c74e27a180d8160bf764c44715ef760f0a62","complete":true,"records":9932,"lastAttemptAt":"2026-11-10T13:21:48.828686+00:00","lastSuccessAt":"2026-11-10T00:04:19.8260565+00:00","error":null,"lastVerifiedAt":"2026-11-10T13:21:48.828686+00:00","snapshotPublishedAt":"2026-11-09T23:48:01+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-26503967ae4379db8f374089589d6e03fb15bd31f820c9e992aaf93840c2236c","complete":true,"records":1971,"lastAttemptAt":"2026-11-10T13:21:48.0645605+00:00","lastSuccessAt":"2026-11-09T21:02:20.472473+00:00","error":null,"lastVerifiedAt":"2026-11-10T13:21:48.0645605+00:00","snapshotPublishedAt":"2026-11-09T20:18:18+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-90debfccd5f97608c3e96ebc37b3b03e91c00adb00e581b0f0dcaea693c0d935","complete":true,"records":3074,"lastAttemptAt":"2026-11-10T13:22:12.0183897+00:00","lastSuccessAt":"2026-11-10T13:22:11.8765745+00:00","error":null,"lastVerifiedAt":"2026-11-10T13:22:12.0183897+00:00","snapshotPublishedAt":"2026-11-10T13:03:15+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-86f40cdda9ca36627f818d0cc8237a8a8c7c22cb687d6747a4ea12bded69e17e","complete":true,"records":231599,"lastAttemptAt":"2026-11-10T13:21:48.3696491+00:00","lastSuccessAt":"2026-11-10T11:25:00.8551311+00:00","error":null,"lastVerifiedAt":"2026-11-10T13:21:48.3696491+00:00","snapshotPublishedAt":"2026-11-10T11:03:07+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}