CVE-2026-99253

io_uring/cancel: rearm local work wake up before sleep

cve-program · severity unknownCVSS unknownCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-99253

Published

In the Linux kernel, the following vulnerability has been resolved: io_uring/cancel: rearm local work wake up before sleep io_uring_try_cancel_requests() sets ->cq_wait_nr to 1 so that the next io_req_local_work_add() wakes the cancelling task. The add that takes the count to zero is the only one that wakes, later ones see a count <= 0 and return. io_uring_cancel_generic() however only becomes TASK_INTERRUPTIBLE much later, so the one wake up can be spent on a running task. That is fine as long as the entry of that add is still queued, as the io_local_work_pending() check then skips the sleep. It is not if the add was delayed after queueing its entry: CPU0 (submitter in exec or exit) CPU1 (io_req_local_work_add) mpscq_push(req A) io_uring_try_cancel_requests() io_run_local_work() // runs req A io_uring_try_cancel_requests() atomic_set(&ctx->cq_wait_nr, 1) atomic_read(&ctx->cq_wait_nr) == 1 count taken, wake_up_state() // task is running, no-op prepare_to_wait(TASK_INTERRUPTIBLE) io_local_work_pending() == false schedule() mpscq_push(req B) cq_wait_nr <= 0, return Only the sleeping task can run req B, so it is stuck in execve() until a signal happens to wake it. An exiting task doesn't even get that. Arm the count again once the task state is set and before the work list is checked, for the rings whose local work this task is the one to run.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-99253

Published

Linux

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "io_uring/cancel.c"
                    ],
                    "versions": [
                        {
                            "version": "d46ab2c98ababa19b41a5709b6921d7b1add7f74",
                            "lessThan": "aaa06bb9fc03384f7cf2dbc3e43f2939cc7791b2",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "d46ab2c98ababa19b41a5709b6921d7b1add7f74",
                            "lessThan": "58ddf0ec707093206a5fe814581ec5aefac8b08a",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "d46ab2c98ababa19b41a5709b6921d7b1add7f74",
                            "lessThan": "76a82c666abf155ad52d5f41043eac77dd3e41d8",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                }

Linux

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "io_uring/cancel.c"
                    ],
                    "versions": [
                        {
                            "version": "7.2",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "7.2",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.14",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3.2",
                            "lessThanOrEqual": "7.3.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.4-rc1",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON