{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47040", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-02-27T18:42:55.968Z", "datePublished": "2024-02-28T08:13:46.557Z", "dateUpdated": "2026-08-05T08:45:40.950Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:45:40.950Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: fix overflows checks in provide buffers\n\nColin reported before possible overflow and sign extension problems in\nio_provide_buffers_prep(). As Linus pointed out previous attempt did nothing\nuseful, see d81269fecb8ce (\"io_uring: fix provide_buffers sign extension\").\n\nDo that with help of check__overflow helpers. And fix struct\nio_provide_buf::len type, as it doesn't make much sense to keep it\nsigned." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached only through local io_uring syscalls (io_uring_setup/io_uring_enter) submitting IORING_OP_PROVIDE_BUFFERS; it is not reachable from network packet processing.\nAC:L - The attacker fully controls sqe addr/len/nbufs and can reliably choose values that overflow len*nbufs (especially on 32-bit, e.g. size wrapping to 0) so the access_ok check validates far less than the registered range.\nPR:L - An unprivileged local user can create an io_uring instance and submit PROVIDE_BUFFERS with no capability requirement; the later io_uring_disabled sysctl did not exist in the affected versions.\nUI:N - Exploitation requires no victim action; the attacker triggers the bug entirely with their own io_uring submissions and subsequent BUFFER_SELECT I/O.\nS:U - Impact is limited to the local kernel's authority (local privilege escalation / memory safety), with no VM, IOMMU, or other security-authority boundary crossed.\nC:H - Overflow bypasses the sole access_ok validation for provided buffers that BUFFER_SELECT paths later trust, enabling registration of ranges that can include kernel addresses and yield arbitrary kernel memory disclosure when used for reads.\nI:H - The same access_ok bypass lets attacker-controlled provided-buffer addresses/lengths be used for kernel writes via BUFFER_SELECT recv/read paths, which is memory corruption exploitable for integrity compromise and code execution.\nA:H - Invalid provided-buffer ranges and signed-length mishandling can cause kernel faults, oopses, or otherwise crash/hang the system when the corrupted buffers are selected for I/O." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/io_uring.c" ], "versions": [ { "version": "efe68c1ca8f49e8c06afd74b699411bfbb8ba1ff", "lessThan": "cbbc13b115b8f18e0a714d89f87fbdc499acfe2d", "status": "affected", "versionType": "git" }, { "version": "efe68c1ca8f49e8c06afd74b699411bfbb8ba1ff", "lessThan": "51bf90901952aaac564bbdb36b2b503050c53dd9", "status": "affected", "versionType": "git" }, { "version": "efe68c1ca8f49e8c06afd74b699411bfbb8ba1ff", "lessThan": "84b8c266c4bfe9ed5128e13253c388deb74b1b03", "status": "affected", "versionType": "git" }, { "version": "efe68c1ca8f49e8c06afd74b699411bfbb8ba1ff", "lessThan": "38134ada0ceea3e848fe993263c0ff6207fd46e7", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/io_uring.c" ], "versions": [ { "version": "5.8", "status": "affected" }, { "version": "0", "lessThan": "5.8", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.37", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.11.21", "lessThanOrEqual": "5.11.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.12.4", "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": "5.8", "versionEndExcluding": "5.10.37" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.8", "versionEndExcluding": "5.11.21" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.8", "versionEndExcluding": "5.12.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.8", "versionEndExcluding": "5.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/cbbc13b115b8f18e0a714d89f87fbdc499acfe2d" }, { "url": "https://git.kernel.org/stable/c/51bf90901952aaac564bbdb36b2b503050c53dd9" }, { "url": "https://git.kernel.org/stable/c/84b8c266c4bfe9ed5128e13253c388deb74b1b03" }, { "url": "https://git.kernel.org/stable/c/38134ada0ceea3e848fe993263c0ff6207fd46e7" } ], "title": "io_uring: fix overflows checks in provide buffers", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:24:39.700Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/cbbc13b115b8f18e0a714d89f87fbdc499acfe2d", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/51bf90901952aaac564bbdb36b2b503050c53dd9", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/84b8c266c4bfe9ed5128e13253c388deb74b1b03", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/38134ada0ceea3e848fe993263c0ff6207fd46e7", "tags": [ "x_transferred" ] } ] }, { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2021-47040", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-09-10T15:57:48.348526Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-09-11T17:32:49.892Z" } } ] } }