{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47244", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-04-10T18:59:19.533Z", "datePublished": "2024-05-21T14:19:42.983Z", "dateUpdated": "2026-08-05T08:46:55.302Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:46:55.302Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: Fix out of bounds when parsing TCP options\n\nThe TCP option parser in mptcp (mptcp_get_options) could read one byte\nout of bounds. When the length is 1, the execution flow gets into the\nloop, reads one byte of the opcode, and if the opcode is neither\nTCPOPT_EOL nor TCPOPT_NOP, it reads one more byte, which exceeds the\nlength of 1.\n\nThis fix is inspired by commit 9609dad263f8 (\"ipv4: tcp_input: fix stack\nout of bounds when parsing TCP options.\")." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H", "baseScore": 8.2, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - mptcp_get_options() parses TCP options from received skbs on MPTCP sockets, including unauthenticated SYNs in subflow_check_req(), established-path mptcp_incoming_options(), and peer SYN-ACKs in subflow_finish_connect(), so a remote peer triggers it via crafted TCP packets.\nAC:L - The attacker fully controls the TCP option bytes and can reliably leave a 1-byte remainder (e.g., NOP padding or a 3-byte option in a 4-byte options area) with a non-EOL/non-NOP opcode so the missing length<2 check is hit every time.\nPR:N - The vulnerable parser runs on the pre-accept SYN path and on ordinary MPTCP segment receive with no credential or capability check; any network peer that can send TCP segments to an MPTCP socket can reach it.\nUI:N - Against an MPTCP listener or an existing MPTCP connection, exploitation is by sending packets alone and does not require a separate user to open a file, mount something, or otherwise interact.\nS:U - Impact is confined to the host kernel that parses the packet; this is ordinary in-kernel memory-safety exposure, not a VM/IOMMU/sandbox boundary cross.\nC:L - The bug is a single-byte out-of-bounds read past the doff-bounded options (into payload, skb tailroom, or skb_shared_info); per guidance that is a bounded OOB read, so confidentiality is Low rather than High.\nI:N - There is no out-of-bounds write; when length==1 the wrongly read opsize is only compared and then the function returns, so it cannot be turned into a memory write or control-flow hijack primitive.\nA:H - Reading one byte past the validated TCP header length can touch memory outside skb->len and can oops/fault depending on skb layout (and is a hard failure under KASAN), so availability impact is scored High under the overestimate rule." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/mptcp/options.c" ], "versions": [ { "version": "cec37a6e41aae7bf3df9a3da783380a4d9325fd8", "lessThan": "73eeba71dc9932970befa009e68272a3d5ec4a58", "status": "affected", "versionType": "git" }, { "version": "cec37a6e41aae7bf3df9a3da783380a4d9325fd8", "lessThan": "76e02b8905d0691e89e104a882f3bba7dd0f6037", "status": "affected", "versionType": "git" }, { "version": "cec37a6e41aae7bf3df9a3da783380a4d9325fd8", "lessThan": "07718be265680dcf496347d475ce1a5442f55ad7", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/mptcp/options.c" ], "versions": [ { "version": "5.6", "status": "affected" }, { "version": "0", "lessThan": "5.6", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.46", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.12.13", "lessThanOrEqual": "5.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.10.46" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.12.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/73eeba71dc9932970befa009e68272a3d5ec4a58" }, { "url": "https://git.kernel.org/stable/c/76e02b8905d0691e89e104a882f3bba7dd0f6037" }, { "url": "https://git.kernel.org/stable/c/07718be265680dcf496347d475ce1a5442f55ad7" } ], "title": "mptcp: Fix out of bounds when parsing TCP options", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "problemTypes": [ { "descriptions": [ { "type": "CWE", "lang": "en", "description": "CWE-noinfo Not enough information" } ] } ], "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 6.2, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE" } }, { "other": { "type": "ssvc", "content": { "timestamp": "2024-05-31T18:50:36.202074Z", "id": "CVE-2021-47244", "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": "2024-11-05T21:23:21.293Z" } }, { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:32:07.998Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/73eeba71dc9932970befa009e68272a3d5ec4a58", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/76e02b8905d0691e89e104a882f3bba7dd0f6037", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/07718be265680dcf496347d475ce1a5442f55ad7", "tags": [ "x_transferred" ] } ] } ] } }