{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-93827", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-18T17:59:28.792Z", "datePublished": "2026-09-24T16:03:05.795Z", "dateUpdated": "2026-09-25T12:43:36.887Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-25T12:43:36.887Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirtio-fs: avoid double-free on failed queue setup\n\nvirtio_fs_setup_vqs() allocates fs->vqs and fs->mq_map before calling\nvirtio_find_vqs(). If virtio_find_vqs() fails, the error path frees both\npointers and returns an error to virtio_fs_probe().\n\nvirtio_fs_probe() then drops the last kobject reference, and\nvirtio_fs_ktype_release() frees fs->vqs and fs->mq_map again. This leaves\ndangling pointers in struct virtio_fs and can trigger a double-free during\nprobe failure cleanup.\n\nSet fs->vqs and fs->mq_map to NULL immediately after kfree() in the\nvirtio_fs_setup_vqs() error path so that the later kobject release sees an\nuninitialized state and kfree(NULL) becomes harmless.\n\nThis can be reproduced when a broken virtio-fs device advertises more\nrequest queues than the transport actually provides. In that case\nvirtio_find_vqs() fails while setting up the extra queue, and the probe\npath reaches the double-free cleanup sequence." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.4, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The triggering field is virtio_fs_config.num_request_queues, read by virtio_cread_le() in virtio_fs_setup_vqs() from virtio_fs_probe() via virtio_dev_probe() after virtio_pci_probe()/register_virtio_device() binds a VIRTIO_ID_FS device; those bytes come from local PCI/MMIO/vDPA config space, not a network protocol message.\nAC:L - A device that advertises more request queues than it exposes makes virtio_find_vqs()->vp_setup_vq() fail (-EINVAL when index >= vp_modern_get_num_queues(), or -ENOENT on queue size 0); virtio_fs_setup_vqs() then kfree's fs->vqs and fs->mq_map and virtio_fs_probe() always kobject_put()s into the second free, with no race.\nPR:N - virtio_fs_probe()/virtio_fs_setup_vqs() have no capable() or credential check; MODULE_DEVICE_TABLE(virtio, id_table) autoloads virtiofs and virtio_dev_probe() binds a VIRTIO_ID_FS device at enumeration or hotplug, so a malicious virtio-fs backend needs no account on the guest.\nUI:N - The double-free runs in the probe error path (virtio_fs_setup_vqs() failure, then kobject_put() into virtio_fs_ktype_release()) when the device appears; virtio_fs_add_instance() and a virtiofs mount are never reached, so no victim must mount or open anything.\nS:U - virtio_fs_ktype_release() double-frees the guest kernel kmalloc objects fs->vqs and fs->mq_map; that is device-to-guest heap corruption inside the same guest kernel, not a write into host virtiofsd or a KVM/IOMMU escape.\nC:H - kfree(fs->vqs) and kfree(fs->mq_map) in virtio_fs_setup_vqs() leave dangling pointers that virtio_fs_ktype_release() frees again; a slab double-free of that virtio_fs_vq array and per-CPU mq_map lets those objects overlap so the attacker can read adjacent kernel heap.\nI:H - The same second kfree of fs->vqs and fs->mq_map corrupts the SLUB freelist for those kmalloc objects and is an arbitrary-free primitive, enabling heap overwrite and control-flow hijack in the guest kernel.\nA:H - Double-free of fs->vqs and fs->mq_map in virtio_fs_ktype_release() after virtio_find_vqs() fails oopses or panics the guest during probe cleanup (KASAN invalid-free, SLUB poisoned-freelist BUG, or panic_on_oops)." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/fuse/virtio_fs.c" ], "versions": [ { "version": "a8f62f50b4e4ea92a938fca2ec1bd108d7f210e9", "lessThan": "3fbc5ee776fefbc6ea34d2518f1f5f90aa2e1dad", "status": "affected", "versionType": "git" }, { "version": "a8f62f50b4e4ea92a938fca2ec1bd108d7f210e9", "lessThan": "20ef4739b329bb09cff11dd2458795a50674658e", "status": "affected", "versionType": "git" }, { "version": "a8f62f50b4e4ea92a938fca2ec1bd108d7f210e9", "lessThan": "6af3330ec5d5fb8c06c04eb520a71cf73ea5a765", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/fuse/virtio_fs.c" ], "versions": [ { "version": "6.9", "status": "affected" }, { "version": "0", "lessThan": "6.9", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "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": "6.9", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.18.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3fbc5ee776fefbc6ea34d2518f1f5f90aa2e1dad" }, { "url": "https://git.kernel.org/stable/c/20ef4739b329bb09cff11dd2458795a50674658e" }, { "url": "https://git.kernel.org/stable/c/6af3330ec5d5fb8c06c04eb520a71cf73ea5a765" } ], "title": "virtio-fs: avoid double-free on failed queue setup", "x_generator": { "engine": "bippy-1.2.0" } } } }