{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40364", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.187Z", "datePublished": "2025-04-18T13:50:24.257Z", "dateUpdated": "2026-08-05T12:09:55.585Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:09:55.585Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: fix io_req_prep_async with provided buffers\n\nio_req_prep_async() can import provided buffers, commit the ring state\nby giving up on that before, it'll be reimported later if needed." } ], "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 vulnerability is reached exclusively through the local io_uring interface — io_uring_setup(2), io_uring_register(2) for PBUF_RING register/unregister, and io_uring_enter(2) SQE submission. No network or adjacent-network path exists into io_req_prep_async().\nAC:L - The attacker controls every element: registering the buffer ring, forcing the prep_async path via IOSQE_ASYNC/IOSQE_IO_LINK/IOSQE_IO_DRAIN on a pollable fd, and freeing the io_buffer_list with IORING_UNREGISTER_PBUF_RING at a moment of their choosing. With IOSQE_IO_LINK the stale req->buf_list is held indefinitely while the link head is pending, making the sequence fully deterministic with no race to win.\nPR:L - There is not a single capable() or CAP_* check on any function in the path — io_register_pbuf_ring(), io_unregister_pbuf_ring(), and buffer-select submission are all unprivileged, and io_uring is enabled by default (kernel.io_uring_disabled=0). Any local unprivileged user, including one inside a container or sandbox, can trigger it.\nUI:N - The entire sequence is performed by the attacker's own process against its own io_uring instance; no victim action, mount, or file open is required.\nS:U - The corrupted io_buffer_list and the resulting privilege escalation are both within the kernel's own security authority; no VM, IOMMU, or hypervisor boundary is crossed.\nC:H - __io_put_kbuf_list()/__io_put_kbuf_ring() read bl->bgid from the freed io_buffer_list and return it to userspace in the CQE IORING_CQE_F_BUFFER field, giving a repeatable 16-bit read oracle over reallocated kmalloc-64 slab contents; on 6.12+ the reallocated bl->buf_ring pointer is dereferenced with attacker-chosen head/mask, extending this to broad kernel memory disclosure.\nI:H - The stale pointer yields a write primitive — bl->head++ on freed memory, and via io_kbuf_commit() with IOBL_INC an attacker-controlled bl->buf_ring is dereferenced to perform buf->len -= len / buf->addr += len, an arbitrary-address write. Heap grooming to reallocate the freed io_buffer_list makes this a viable local privilege escalation.\nA:H - Dereferencing and incrementing fields of a kfree'd io_buffer_list, plus unsynchronized bl->head updates from io-wq without uring_lock, corrupts arbitrary slab objects and reliably produces oopses, KASAN splats, or a kernel panic." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "io_uring/io_uring.c" ], "versions": [ { "version": "c7fb19428d67dd0a2a78a4f237af01d39c78dc5a", "lessThan": "233b210a678bddf8b49b02a070074a52b87e6d43", "status": "affected", "versionType": "git" }, { "version": "c7fb19428d67dd0a2a78a4f237af01d39c78dc5a", "lessThan": "a1b17713b32c75a90132ea2f92b1257f3bbc20f3", "status": "affected", "versionType": "git" }, { "version": "c7fb19428d67dd0a2a78a4f237af01d39c78dc5a", "lessThan": "b86f1d51731e621e83305dc9564ae14c9ef752bf", "status": "affected", "versionType": "git" }, { "version": "c7fb19428d67dd0a2a78a4f237af01d39c78dc5a", "lessThan": "a94592ec30ff67dc36c424327f1e0a9ceeeb9bd3", "status": "affected", "versionType": "git" }, { "version": "c7fb19428d67dd0a2a78a4f237af01d39c78dc5a", "lessThan": "35ae7910c349fb3c60439992e2e0e79061e95382", "status": "affected", "versionType": "git" }, { "version": "c7fb19428d67dd0a2a78a4f237af01d39c78dc5a", "lessThan": "f0ef94553868d07c1b14d7743a7e2553e5a831a3", "status": "affected", "versionType": "git" }, { "version": "c7fb19428d67dd0a2a78a4f237af01d39c78dc5a", "lessThan": "d63b0e8a628e62ca85a0f7915230186bb92f8bb4", "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/io_uring.c" ], "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.129", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.78", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.14", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13.3", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14", "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": "5.19", "versionEndExcluding": "6.1.129" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.1.129" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.6.78" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.6.78" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.14" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.13.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.14" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/233b210a678bddf8b49b02a070074a52b87e6d43" }, { "url": "https://git.kernel.org/stable/c/a1b17713b32c75a90132ea2f92b1257f3bbc20f3" }, { "url": "https://git.kernel.org/stable/c/b86f1d51731e621e83305dc9564ae14c9ef752bf" }, { "url": "https://git.kernel.org/stable/c/a94592ec30ff67dc36c424327f1e0a9ceeeb9bd3" }, { "url": "https://git.kernel.org/stable/c/35ae7910c349fb3c60439992e2e0e79061e95382" }, { "url": "https://git.kernel.org/stable/c/f0ef94553868d07c1b14d7743a7e2553e5a831a3" }, { "url": "https://git.kernel.org/stable/c/d63b0e8a628e62ca85a0f7915230186bb92f8bb4" } ], "title": "io_uring: fix io_req_prep_async with provided buffers", "x_generator": { "engine": "bippy-1.2.0" } } } }