{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-56709", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-27T15:00:39.857Z", "datePublished": "2024-12-29T08:42:58.403Z", "dateUpdated": "2026-08-05T11:46:12.483Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:46:12.483Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: check if iowq is killed before queuing\n\ntask work can be executed after the task has gone through io_uring\ntermination, whether it's the final task_work run or the fallback path.\nIn this case, task work will find ->io_wq being already killed and\nnull'ed, which is a problem if it then tries to forward the request to\nio_queue_iowq(). Make io_queue_iowq() fail requests in this case.\n\nNote that it also checks PF_KTHREAD, because the user can first close\na DEFER_TASKRUN ring and shortly after kill the task, in which case\n->iowq check would race." } ], "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 purely through the io_uring syscall interface (io_uring_setup/io_uring_enter, SQE submission, and close(2) of the ring fd), which requires local access to the machine. Per kernel scoring guidance io_uring bugs are Local.\nAC:L - The attacker controls both sides of the race — they choose exactly when to close the DEFER_TASKRUN ring (driving the request into the PF_KTHREAD fallback worker) and when to exit the submitting task (driving io_wq_put_and_exit/kfree), and can retry the whole sequence in a fresh process arbitrarily many times. The NULL-io_wq/BUG_ON variant is essentially deterministic once the exit ordering is arranged.\nPR:L - Any unprivileged local user with default io_uring access can create the ring, submit an IOSQE_ASYNC/IOSQE_IO_DRAIN request (REQ_F_FORCE_ASYNC), and trigger the exit race; no capabilities, root, or user-namespace tricks are required.\nUI:N - The entire sequence is performed by the attacker's own process and threads with no victim action of any kind.\nS:U - The corruption and its consequences are confined to the Linux kernel's own security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The freed struct io_wq is read back after kfree (wq->state, wq->acct[], wq->free_list, wq->task, wq->do_work/free_work), so an attacker who reclaims the kmalloc-1k slot obtains a use-after-free read primitive over kernel heap contents, and per guidance a UAF is scored High.\nI:H - io_run_cancel() invokes wq->do_work(work) and wq->free_work(work) — indirect calls through function pointers read from the freed, attacker-reclaimable allocation — and io_wq_insert_work() writes list pointers into that freed memory, giving control-flow hijack and write primitives suitable for privilege escalation.\nA:H - The NULL-io_wq path hits BUG_ON() for a guaranteed kernel oops (full panic with panic_on_oops), and because it fires inside io_fallback_req_func() while holding ctx->uring_lock the mutex is leaked, permanently hanging io_ring_exit_work and any task touching that ring; the UAF variant additionally crashes on freed memory." } ] } ], "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": "773af69121ecc6c53d192661af8d53bb3db028ae", "lessThan": "534d59ab38010aada88390db65985e65d0de7d9e", "status": "affected", "versionType": "git" }, { "version": "773af69121ecc6c53d192661af8d53bb3db028ae", "lessThan": "2ca94c8de36091067b9ce7527ae8db3812d38781", "status": "affected", "versionType": "git" }, { "version": "773af69121ecc6c53d192661af8d53bb3db028ae", "lessThan": "4f95a2186b7f2af09331e1e8069bcaf34fe019cf", "status": "affected", "versionType": "git" }, { "version": "773af69121ecc6c53d192661af8d53bb3db028ae", "lessThan": "dbd2ca9367eb19bc5e269b8c58b0b1514ada9156", "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": "5.14", "status": "affected" }, { "version": "0", "lessThan": "5.14", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.122", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.68", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.7", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13", "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": "5.14", "versionEndExcluding": "6.1.122" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.6.68" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.12.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/534d59ab38010aada88390db65985e65d0de7d9e" }, { "url": "https://git.kernel.org/stable/c/2ca94c8de36091067b9ce7527ae8db3812d38781" }, { "url": "https://git.kernel.org/stable/c/4f95a2186b7f2af09331e1e8069bcaf34fe019cf" }, { "url": "https://git.kernel.org/stable/c/dbd2ca9367eb19bc5e269b8c58b0b1514ada9156" } ], "title": "io_uring: check if iowq is killed before queuing", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:53:02.240Z" } } ] } }