{"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"}}}}