{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-80548", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.766Z", "datePublished": "2026-08-26T14:37:18.759Z", "dateUpdated": "2026-08-27T05:01:35.892Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-27T05:01:35.892Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio_ccw: Selectively expand io_mutex\n\nThe io_mutex was defined to serialize the io_regions, but then has\nalso sort of been associated with the I/O themselves because of\nthe close relationship they share.\n\nWith the handful of races that are possible, the choices are either to:\n A) expand the scope of io_mutex to close these remaining windows, or\n B) reduce the scope of io_mutex to just io_region, and introduce a new\n lock mechanism for the remaining I/O resources\n\nThis patch implements A, since B brings with it a lot more interactions\nthat would need to be tracked and kept in a correct hierarchy. It also\ntakes advantage of the workqueue element for cp_free() that now gets\ncalled out of fsm_notoper(), which could be invoked out of an interrupt\ncontext and thus cannot acquire a mutex itself."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The bug is reached only through local VFIO mediated-device syscalls (read/write/ioctl on vfio-ccw device fds) and deferred work from hardware I/O interrupts and channel-path events; vfio-ccw has no network, Bluetooth, or physical-bus entry point.\nAC:L - The VFIO client controls both sides of each race window: it can submit channel I/O, close or reset the device, and trigger DMA unmap while io_work, notoper_work, or fsm_close concurrently run cp_free, cp_update_scsw, or cp_iova_pinned without full io_mutex protection, and retry to win reliably.\nPR:L - Exploitation requires an opened vfio-ccw mdev device fd (typical QEMU/libvirt VM operator or delegated /dev/vfio holder on IBM Z passthrough hosts), not init-namespace root; mdev creation is admin setup, but triggering the races needs only that delegated VFIO client access.\nUI:N - No separate victim action is required; once vfio-ccw passthrough is configured, the attacker issues concurrent channel I/O, region access, device close/reset, or DMA unmap without needing another user to mount media or interact.\nS:C - On IBM Z/LinuxONE, vfio-ccw passes DASD/CCW subchannels into KVM guests; guest-driven channel I/O and path events trigger host interrupt/workqueue activity concurrent with VFIO client teardown, corrupting hypervisor kernel memory outside the VM security boundary.\nC:H - cp_free racing with cp_update_scsw, cp_iova_pinned, and io_region access without io_mutex causes use-after-free on ccwchain_list and page_array structures; per kernel UAF guidance this enables attacker-influenced heap reuse and arbitrary kernel read primitives.\nI:H - Concurrent cp_free during cp_init, page_array_unpin_free, memcpy into io_region, and mutex operations on freed channel_program memory provides heap-sprayable arbitrary write and control-flow hijack potential beyond a simple crash.\nA:H - Use-after-free and double-free of channel program structures during concurrent I/O completion, not-operational cleanup, or device close can immediately oops or panic the host kernel from invalid list/mutex access, and successful exploitation can crash or hang the system."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/s390/cio/vfio_ccw_chp.c", "drivers/s390/cio/vfio_ccw_cp.c", "drivers/s390/cio/vfio_ccw_drv.c", "drivers/s390/cio/vfio_ccw_fsm.c", "drivers/s390/cio/vfio_ccw_private.h"], "versions": [{"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "lessThan": "f72a51810d49411bd8cad0c2df8592320a2fe5cc", "status": "affected", "versionType": "git"}, {"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "lessThan": "2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd", "status": "affected", "versionType": "git"}, {"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "lessThan": "b6aecea4b2b246f9fbd98a5712daa1193a60818e", "status": "affected", "versionType": "git"}, {"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "lessThan": "2a5ac0c0f1f7da33929211a2e41911bf72ee35d8", "status": "affected", "versionType": "git"}, {"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "lessThan": "34f4feff3e90bd09308fad0974e97113b23b812a", "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/s390/cio/vfio_ccw_chp.c", "drivers/s390/cio/vfio_ccw_cp.c", "drivers/s390/cio/vfio_ccw_drv.c", "drivers/s390/cio/vfio_ccw_fsm.c", "drivers/s390/cio/vfio_ccw_private.h"], "versions": [{"version": "5.2", "status": "affected"}, {"version": "0", "lessThan": "5.2", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.153", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.105", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.46", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.10", "lessThanOrEqual": "7.1.*", "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": "5.2", "versionEndExcluding": "6.6.153"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.2", "versionEndExcluding": "6.12.105"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.2", "versionEndExcluding": "6.18.46"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.2", "versionEndExcluding": "7.1.10"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.2", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc"}, {"url": "https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd"}, {"url": "https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e"}, {"url": "https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8"}, {"url": "https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a"}], "title": "s390/vfio_ccw: Selectively expand io_mutex", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/s390/cio/vfio_ccw_chp.c", "drivers/s390/cio/vfio_ccw_cp.c", "drivers/s390/cio/vfio_ccw_drv.c", "drivers/s390/cio/vfio_ccw_fsm.c", "drivers/s390/cio/vfio_ccw_private.h"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "f72a51810d49411bd8cad0c2df8592320a2fe5cc", "status": "affected", "version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "versionType": "git"}, {"lessThan": "2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd", "status": "affected", "version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "versionType": "git"}, {"lessThan": "b6aecea4b2b246f9fbd98a5712daa1193a60818e", "status": "affected", "version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "versionType": "git"}, {"lessThan": "2a5ac0c0f1f7da33929211a2e41911bf72ee35d8", "status": "affected", "version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "versionType": "git"}, {"lessThan": "34f4feff3e90bd09308fad0974e97113b23b812a", "status": "affected", "version": "4f76617378ee97c557b526cb58d3c61eb0a9c963", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/s390/cio/vfio_ccw_chp.c", "drivers/s390/cio/vfio_ccw_cp.c", "drivers/s390/cio/vfio_ccw_drv.c", "drivers/s390/cio/vfio_ccw_fsm.c", "drivers/s390/cio/vfio_ccw_private.h"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.2"}, {"lessThan": "5.2", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.153", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.105", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.46", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.10", "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\ns390/vfio_ccw: Selectively expand io_mutex\n\nThe io_mutex was defined to serialize the io_regions, but then has\nalso sort of been associated with the I/O themselves because of\nthe close relationship they share.\n\nWith the handful of races that are possible, the choices are either to:\n A) expand the scope of io_mutex to close these remaining windows, or\n B) reduce the scope of io_mutex to just io_region, and introduce a new\n lock mechanism for the remaining I/O resources\n\nThis patch implements A, since B brings with it a lot more interactions\nthat would need to be tracked and kept in a correct hierarchy. It also\ntakes advantage of the workqueue element for cp_free() that now gets\ncalled out of fsm_notoper(), which could be invoked out of an interrupt\ncontext and thus cannot acquire a mutex itself."}], "id": "CVE-2026-80548", "lastModified": "2026-08-27T06:17:36.697", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 8.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.0, "impactScore": 6.0, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-26T15:17:09.200", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{}

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