CVE-2026-97478

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-97478", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-24T16:01:01.149Z", "datePublished": "2026-09-24T16:04:20.263Z", "dateUpdated": "2026-10-30T12:36:59.771Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-30T12:36:59.771Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirt: acrn: Fix irqfd use-after-free during eventfd shutdown\n\nacrn_irqfd_deassign() and the eventfd EPOLLHUP wakeup can race and free\nthe same struct hsm_irqfd:\n\n CPU0 CPU1\n ---- ----\n eventfd_release()\n wake_up_poll(EPOLLHUP)\n hsm_irqfd_wakeup()\n queue_work(&irqfd->shutdown)\n acrn_irqfd_deassign()\n hsm_irqfd_shutdown()\n list_del_init()\n eventfd_ctx_remove_wait_queue()\n eventfd_ctx_put()\n kfree(irqfd)\n hsm_irqfd_shutdown_work()\n container_of(work, ..., shutdown)\n irqfd->vm <-- use-after-free\n\nThe deassign path freed the irqfd while a shutdown work item was\nalready queued by EPOLLHUP (or vice versa), so the work item could\nresurrect a dangling pointer through container_of().\n\nSwitch to the lifetime model used by KVM irqfds:\n\n - Deassign/deinit only deactivate the irqfd: remove it from vm->irqfds\n under irqfds_lock and queue the cleanup work.\n - hsm_irqfd_shutdown_work() becomes the sole owner that unhooks the\n eventfd waitqueue entry, drops the eventfd reference and frees the\n irqfd.\n - A new HSM_IRQFD_FLAG_SHUTDOWN bit guarded by test_and_set_bit()\n ensures the cleanup work is queued at most once, no matter how many\n of {EPOLLHUP, deassign, deinit} fire concurrently. This is safe to\n call from the waitqueue callback, which runs with wqh->lock held and\n IRQs disabled and therefore cannot take irqfds_lock.\n - acrn_irqfd_deassign() flushes vm->irqfd_wq before returning so the\n eventfd is fully detached on return. acrn_irqfd_deinit() deactivates\n every irqfd, flushes the workqueue and only then destroys it, so no\n path can queue_work() onto a torn-down workqueue.\n - acrn_irqfd_assign() now installs the eventfd waitqueue entry and\n publishes the irqfd to vm->irqfds under irqfds_lock, so the irqfd is\n never visible to deassign/deinit before its waitqueue entry is in\n place, and any EPOLLHUP that fires in the assign window queues\n cleanup work that blocks on irqfds_lock until publication is done."}], "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 UAF is reached from ioctl(ACRN_IOCTL_IRQFD) on /dev/acrn_hsm: acrn_dev_ioctl() copy_from_user()s struct acrn_irqfd and calls acrn_irqfd_config() \u2192 acrn_irqfd_assign()/acrn_irqfd_deassign(), while close() of that eventfd hits eventfd_release() \u2192 hsm_irqfd_wakeup(). No remote protocol carries the fd, flags, or EPOLLHUP.\nAC:L - The attacker owns both sides: one thread ioctl(ACRN_IOCTL_IRQFD) with ACRN_IRQFD_FLAG_DEASSIGN so acrn_irqfd_deassign() \u2192 hsm_irqfd_shutdown() kfree()s the hsm_irqfd, while another close()s a dup of the same eventfd so eventfd_release() \u2192 wake_up_poll(EPOLLHUP) \u2192 hsm_irqfd_wakeup() queues hsm_irqfd_shutdown_work(); the window is retryable.\nPR:L - acrn_dev_open(), acrn_dev_ioctl() and acrn_irqfd_config() have no capable()/CAP_* gate; only /dev/acrn_hsm DAC applies. ACRN Service VM deployments grant that node to the deprivileged acrn-dm device-model account (as with /dev/kvm), so a local user with that fd can CREATE_VM and IRQFD without init-namespace root.\nUI:N - The attacker opens /dev/acrn_hsm, ioctl(ACRN_IOCTL_CREATE_VM) then ACRN_IOCTL_IRQFD assign, and races close() of its own eventfd against deassign (or acrn_dev_release() \u2192 acrn_irqfd_deinit()); no other user must mount, open, or click.\nS:U - hsm_irqfd_shutdown_work() uses the freed struct hsm_irqfd in the Service VM kernel that runs acrn_dev_ioctl(). The attacker is already a Service VM process issuing HSM ioctls, not a User VM guest crossing into the ACRN hypervisor, so impact stays in one kernel authority.\nC:H - After acrn_irqfd_deassign() kfree()s the hsm_irqfd, hsm_irqfd_shutdown_work() container_of()s the queued work_struct and reads irqfd->vm (and later irqfd->eventfd) from the freed kmalloc object. Reclaiming that slot lets the attacker disclose reallocated kernel heap through those dangling loads.\nI:H - The same UAF lets hsm_irqfd_shutdown_work() mutex_lock(&irqfd->vm->irqfds_lock), list_del_init(&irqfd->list) and eventfd_ctx_put(irqfd->eventfd) on attacker-reclaimed hsm_irqfd fields, which is an arbitrary write / wait-queue function-pointer hijack, plus a second kfree of the sprayed object.\nA:H - hsm_irqfd_shutdown_work() loading irqfd->vm after hsm_irqfd_shutdown() kfree()s it oopses on a dangling pointer or corrupts the irqfds mutex/list; the EPOLLHUP work versus deassign kfree race in the commit is a Service VM kernel panic even without a successful spray."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/virt/acrn/irqfd.c"], "versions": [{"version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "lessThan": "dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48", "status": "affected", "versionType": "git"}, {"version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "lessThan": "6e9e007ee1dfb54bc2d070550308077ec28dbaec", "status": "affected", "versionType": "git"}, {"version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "lessThan": "0e1152f689847b9db2f05454775d34610c1424c2", "status": "affected", "versionType": "git"}, {"version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "lessThan": "d8156aacfcabb81f52c20ef89094945434d08079", "status": "affected", "versionType": "git"}, {"version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "lessThan": "666c7f9e07925aa0863348f960e09bb89f8f05a3", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/virt/acrn/irqfd.c"], "versions": [{"version": "5.12", "status": "affected"}, {"version": "0", "lessThan": "5.12", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.191", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.114", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "5.12", "versionEndExcluding": "6.1.191"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.6.160"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.12.114"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.18.53"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48"}, {"url": "https://git.kernel.org/stable/c/6e9e007ee1dfb54bc2d070550308077ec28dbaec"}, {"url": "https://git.kernel.org/stable/c/0e1152f689847b9db2f05454775d34610c1424c2"}, {"url": "https://git.kernel.org/stable/c/d8156aacfcabb81f52c20ef89094945434d08079"}, {"url": "https://git.kernel.org/stable/c/666c7f9e07925aa0863348f960e09bb89f8f05a3"}], "title": "virt: acrn: Fix irqfd use-after-free during eventfd shutdown", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/virt/acrn/irqfd.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48", "status": "affected", "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "versionType": "git"}, {"lessThan": "6e9e007ee1dfb54bc2d070550308077ec28dbaec", "status": "affected", "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "versionType": "git"}, {"lessThan": "0e1152f689847b9db2f05454775d34610c1424c2", "status": "affected", "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "versionType": "git"}, {"lessThan": "d8156aacfcabb81f52c20ef89094945434d08079", "status": "affected", "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "versionType": "git"}, {"lessThan": "666c7f9e07925aa0863348f960e09bb89f8f05a3", "status": "affected", "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/virt/acrn/irqfd.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.12"}, {"lessThan": "5.12", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.191", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.160", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.114", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.53", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirt: acrn: Fix irqfd use-after-free during eventfd shutdown\n\nacrn_irqfd_deassign() and the eventfd EPOLLHUP wakeup can race and free\nthe same struct hsm_irqfd:\n\n CPU0 CPU1\n ---- ----\n eventfd_release()\n wake_up_poll(EPOLLHUP)\n hsm_irqfd_wakeup()\n queue_work(&irqfd->shutdown)\n acrn_irqfd_deassign()\n hsm_irqfd_shutdown()\n list_del_init()\n eventfd_ctx_remove_wait_queue()\n eventfd_ctx_put()\n kfree(irqfd)\n hsm_irqfd_shutdown_work()\n container_of(work, ..., shutdown)\n irqfd->vm <-- use-after-free\n\nThe deassign path freed the irqfd while a shutdown work item was\nalready queued by EPOLLHUP (or vice versa), so the work item could\nresurrect a dangling pointer through container_of().\n\nSwitch to the lifetime model used by KVM irqfds:\n\n - Deassign/deinit only deactivate the irqfd: remove it from vm->irqfds\n under irqfds_lock and queue the cleanup work.\n - hsm_irqfd_shutdown_work() becomes the sole owner that unhooks the\n eventfd waitqueue entry, drops the eventfd reference and frees the\n irqfd.\n - A new HSM_IRQFD_FLAG_SHUTDOWN bit guarded by test_and_set_bit()\n ensures the cleanup work is queued at most once, no matter how many\n of {EPOLLHUP, deassign, deinit} fire concurrently. This is safe to\n call from the waitqueue callback, which runs with wqh->lock held and\n IRQs disabled and therefore cannot take irqfds_lock.\n - acrn_irqfd_deassign() flushes vm->irqfd_wq before returning so the\n eventfd is fully detached on return. acrn_irqfd_deinit() deactivates\n every irqfd, flushes the workqueue and only then destroys it, so no\n path can queue_work() onto a torn-down workqueue.\n - acrn_irqfd_assign() now installs the eventfd waitqueue entry and\n publishes the irqfd to vm->irqfds under irqfds_lock, so the irqfd is\n never visible to deassign/deinit before its waitqueue entry is in\n place, and any EPOLLHUP that fires in the assign window queues\n cleanup work that blocks on irqfds_lock until publication is done."}], "id": "CVE-2026-97478", "lastModified": "2026-10-30T13:21:04.313", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-24T17:17:25.183", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0e1152f689847b9db2f05454775d34610c1424c2"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/666c7f9e07925aa0863348f960e09bb89f8f05a3"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6e9e007ee1dfb54bc2d070550308077ec28dbaec"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d8156aacfcabb81f52c20ef89094945434d08079"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: virt: acrn: Fix irqfd use-after-free during eventfd shutdown", "id": "2540419", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2540419"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-825", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nvirt: acrn: Fix irqfd use-after-free during eventfd shutdown\nacrn_irqfd_deassign() and the eventfd EPOLLHUP wakeup can race and free\nthe same struct hsm_irqfd:\nCPU0 CPU1\n---- ----\neventfd_release()\nwake_up_poll(EPOLLHUP)\nhsm_irqfd_wakeup()\nqueue_work(&irqfd->shutdown)\nacrn_irqfd_deassign()\nhsm_irqfd_shutdown()\nlist_del_init()\neventfd_ctx_remove_wait_queue()\neventfd_ctx_put()\nkfree(irqfd)\nhsm_irqfd_shutdown_work()\ncontainer_of(work, ..., shutdown)\nirqfd->vm <-- use-after-free\nThe deassign path freed the irqfd while a shutdown work item was\nalready queued by EPOLLHUP (or vice versa), so the work item could\nresurrect a dangling pointer through container_of().\nSwitch to the lifetime model used by KVM irqfds:\n- Deassign/deinit only deactivate the irqfd: remove it from vm->irqfds\nunder irqfds_lock and queue the cleanup work.\n- hsm_irqfd_shutdown_work() becomes the sole owner that unhooks the\neventfd waitqueue entry, drops the eventfd reference and frees the\nirqfd.\n- A new HSM_IRQFD_FLAG_SHUTDOWN bit guarded by test_and_set_bit()\nensures the cleanup work is queued at most once, no matter how many\nof {EPOLLHUP, deassign, deinit} fire concurrently. This is safe to\ncall from the waitqueue callback, which runs with wqh->lock held and\nIRQs disabled and therefore cannot take irqfds_lock.\n- acrn_irqfd_deassign() flushes vm->irqfd_wq before returning so the\neventfd is fully detached on return. acrn_irqfd_deinit() deactivates\nevery irqfd, flushes the workqueue and only then destroys it, so no\npath can queue_work() onto a torn-down workqueue.\n- acrn_irqfd_assign() now installs the eventfd waitqueue entry and\npublishes the irqfd to vm->irqfds under irqfds_lock, so the irqfd is\nnever visible to deassign/deinit before its waitqueue entry is in\nplace, and any EPOLLHUP that fires in the assign window queues\ncleanup work that blocks on irqfds_lock until publication is done.", "A flaw was found in the Linux kernel's ACRN hypervisor driver. A race condition during interrupt file descriptor (irqfd) shutdown can lead to a use-after-free memory error when an irqfd is deassigned while event notification cleanup is concurrently processed. A local attacker could exploit this vulnerability to cause a system crash, resulting in a Denial of Service (DoS), or potentially escalate privileges."], "name": "CVE-2026-97478", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-09-24T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-97478\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-97478\nhttps://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97478.mbox"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,d8156aacfcabb81f52c20ef89094945434d08079)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,666c7f9e07925aa0863348f960e09bb89f8f05a3)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,6.18.53)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.53,6.18.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-24T23:30:17.305057+00:00", "updated": "2026-10-01T12:30:07.589874+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"], "weaknesses": ["CWE-416", "CWE-825"]}