{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40047", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.156Z", "datePublished": "2025-10-28T11:48:24.625Z", "dateUpdated": "2026-08-05T12:07:20.600Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:07:20.600Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/waitid: always prune wait queue entry in io_waitid_wait()\n\nFor a successful return, always remove our entry from the wait queue\nentry list. Previously this was skipped if a cancelation was in\nprogress, but this can race with another invocation of the wait queue\nentry callback." } ], "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 through the io_uring syscall interface (`io_uring_setup`/`io_uring_enter` submitting an `IORING_OP_WAITID` SQE) plus process-management signals, all of which require local access to the system. Per kernel scoring guidance, io_uring bugs are Local.\nAC:L - The attacker controls both sides of the race: it drives the wait-queue wakeups at arbitrary rate by forking children and looping SIGSTOP/SIGCONT (`do_notify_parent_cldstop` → `__wake_up_parent`), while concurrently submitting `IORING_OP_ASYNC_CANCEL` or tearing down the ring from another thread to grab the competing reference. syzbot produced a working reproducer and confirmed the fix, showing the window is hit reliably.\nPR:L - Any unprivileged local user can create an io_uring ring — `sysctl_io_uring_disabled` defaults to 0 and `IORING_OP_WAITID` carries no capability check — and waiting on one's own forked children needs no privilege at all. No capabilities, user namespaces, or root are required.\nUI:N - The attacker's own process performs every step: submitting the waitid SQE, forking and signalling the children that generate wakeups, and issuing the concurrent cancel. No action by any other user is needed.\nS:U - The use-after-free corrupts kernel heap memory and control flow within the same kernel security authority, yielding standard local privilege escalation. No VM, IOMMU, or other security-boundary crossing is involved.\nC:H - This is a use-after-free on a `struct io_waitid_async` allocated from a general-purpose kmalloc slab, which the attacker can reclaim and shape via heap spraying. The stale wait-queue entry is then dereferenced by `__wake_up_common()` and `list_del_init()`, giving a read primitive over reclaimed kernel memory that can be leveraged for arbitrary kernel memory disclosure.\nI:H - `list_del_init()` on the freed entry performs `prev->next = next; next->prev = prev` using pointers read from attacker-reclaimed memory, yielding a controlled write of a controlled pointer to a controlled address. Additionally `__wake_up_common()` calls `curr->func(...)` on the freed entry, providing a direct indirect-call/control-flow hijack primitive leading to kernel code execution.\nA:H - Even without weaponization, the dangling wait-queue entry and the list-corrupting `list_del_init()` on freed memory produce KASAN splats, list debug BUGs, and kernel oopses/panics — this is exactly how syzbot detected it. The race can be re-triggered in a tight loop, so an unprivileged user can crash the machine at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "io_uring/waitid.c" ], "versions": [ { "version": "f31ecf671ddc498f20219453395794ff2383e06b", "lessThan": "696ba6032081e617564a8113a001b8d7943cb928", "status": "affected", "versionType": "git" }, { "version": "f31ecf671ddc498f20219453395794ff2383e06b", "lessThan": "3e2205db2f0608898d535da1964e1b376aacfdaa", "status": "affected", "versionType": "git" }, { "version": "f31ecf671ddc498f20219453395794ff2383e06b", "lessThan": "2f8229d53d984c6a05b71ac9e9583d4354e3b91f", "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/waitid.c" ], "versions": [ { "version": "6.7", "status": "affected" }, { "version": "0", "lessThan": "6.7", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.53", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17.3", "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": "6.7", "versionEndExcluding": "6.12.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.17.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/696ba6032081e617564a8113a001b8d7943cb928" }, { "url": "https://git.kernel.org/stable/c/3e2205db2f0608898d535da1964e1b376aacfdaa" }, { "url": "https://git.kernel.org/stable/c/2f8229d53d984c6a05b71ac9e9583d4354e3b91f" } ], "title": "io_uring/waitid: always prune wait queue entry in io_waitid_wait()", "x_generator": { "engine": "bippy-1.2.0" } } } }