{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2025-40291",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2025-04-16T07:20:57.185Z",
        "datePublished": "2025-12-08T00:46:14.601Z",
        "dateUpdated": "2026-08-05T12:09:17.336Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-08-05T12:09:17.336Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: fix regbuf vector size truncation\n\nThere is a report of io_estimate_bvec_size() truncating the calculated\nnumber of segments that leads to corruption issues. Check it doesn't\noverflow \"int\"s used later. Rough but simple, can be improved on top."
                }
            ],
            "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 vulnerable code is reached only through io_uring SQE submission (READV_FIXED/WRITEV_FIXED, zerocopy sendmsg, fixed uring_cmd), a local syscall interface; there is no remote network trigger despite one caller being in net.c.\nAC:L - The attacker fully controls the registered buffer and the iovec lengths that drive the truncated size estimate, so the under-allocation and out-of-bounds write are triggered deterministically with no race or uncontrolled condition.\nPR:L - Any unprivileged local user can create an io_uring instance and register buffers; io_uring is enabled by default (sysctl_io_uring_disabled=0) and requires no capabilities.\nUI:N - The attacker triggers the flaw entirely through their own io_uring operations with no victim interaction required.\nS:U - The corruption occurs within kernel heap memory in the same security authority; there is no crossing of a VM/IOMMU/sandbox boundary.\nC:H - The integer-truncation-driven heap out-of-bounds access corrupts adjacent kernel objects and can be leveraged for arbitrary kernel-memory disclosure.\nI:H - The under-sized bvec allocation causes an out-of-bounds write of attacker-influenced bio_vec structures past the buffer, giving a heap write primitive exploitable for control-flow hijacking.\nA:H - The out-of-bounds heap write reliably corrupts kernel memory, causing oops/panic and denial of service."
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "io_uring/rsrc.c"
                    ],
                    "versions": [
                        {
                            "version": "9ef4cbbcb4ac3786a1a4164507511b76b2a572c5",
                            "lessThan": "826ce37a842633efe1bb763e4b13045d74060d72",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "9ef4cbbcb4ac3786a1a4164507511b76b2a572c5",
                            "lessThan": "146eb58629f45f8297e83d69e64d4eea4b28d972",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "io_uring/rsrc.c"
                    ],
                    "versions": [
                        {
                            "version": "6.15",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.15",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.17.8",
                            "lessThanOrEqual": "6.17.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18",
                            "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": "6.15",
                                    "versionEndExcluding": "6.17.8"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.15",
                                    "versionEndExcluding": "6.18"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/826ce37a842633efe1bb763e4b13045d74060d72"
                },
                {
                    "url": "https://git.kernel.org/stable/c/146eb58629f45f8297e83d69e64d4eea4b28d972"
                }
            ],
            "title": "io_uring: fix regbuf vector size truncation",
            "x_generator": {
                "engine": "bippy-1.2.0"
            }
        }
    }
}