{"api_version":"1","generated_at":"2026-09-25T22:18:34+00:00","cve":"CVE-2026-98156","urls":{"html":"https://cve.report/CVE-2026-98156","api":"https://cve.report/api/cve/CVE-2026-98156.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98156","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98156"},"summary":{"title":"drm/virtio: use the DMA API for resource backing on Xen","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/virtio: use the DMA API for resource backing on Xen\n\nOn a Xen PV domain page addresses bear no relation to the real machine\naddresses the host would have to use to reach it.\nvirtio_ring.c handles this correctly, vring_use_map_api() returns true\nfor any xen_domain() regardless of VIRTIO_F_ACCESS_PLATFORM.\n\nvirtio-gpu makes the same decision independently, but its copy\nlooks only at the feature bit:\n\n\tbool use_dma_api = !virtio_has_dma_quirk(vgdev->vdev);\n\nQEMU does not set iommu_platform on virtio-vga by default, so\nVIRTIO_F_ACCESS_PLATFORM is not negotiated, use_dma_api is false, and\nvirtio_gpu_object_shmem_init() describes the framebuffer's backing pages\nto the host with sg_phys().  Those are guest-physical addresses. In a PV\ndomain they resolve, on the host side, to pages belonging to some other\ndomain, so the host scans out unrelated memory.\n\nMove the decision into virtio_gpu_use_dma_api() and give it the\nxen_domain() check, like vring_use_map_api() has. This\nadditionally enables the dma_sync_sgtable_for_device() calls in\nvirtgpu_vq.c, which are required for correctness whenever swiotlb\nis in play.\n\nReproduced with a Xen 4.21 PV dom0 nested inside QEMU 8.2 with\nvirtio-vga, on both a distro 6.8 kernel and 6.18 LTS. A PVH dom0\nworks fine and doesn't need this fix because it is identity-mapped,\nonly PV dom0s are affected.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-25 11:17:47","updated_at":"2026-09-25 15:18:07"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/93c557e947ef0040004b1ac6a1c1265d79a957e1","name":"https://git.kernel.org/stable/c/93c557e947ef0040004b1ac6a1c1265d79a957e1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/455184dbe9652d01470d3c5cf5edd09a7a673a99","name":"https://git.kernel.org/stable/c/455184dbe9652d01470d3c5cf5edd09a7a673a99","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6a736d2f9d0c6e6217fe7532bc4c50ceca71db78","name":"https://git.kernel.org/stable/c/6a736d2f9d0c6e6217fe7532bc4c50ceca71db78","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98156","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98156","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a3b815f09bb846255c458c181b8a5b1cc66891b4 93c557e947ef0040004b1ac6a1c1265d79a957e1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a3b815f09bb846255c458c181b8a5b1cc66891b4 455184dbe9652d01470d3c5cf5edd09a7a673a99 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a3b815f09bb846255c458c181b8a5b1cc66891b4 6a736d2f9d0c6e6217fe7532bc4c50ceca71db78 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.20","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.53 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.7 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/gpu/drm/virtio/virtgpu_drv.h","drivers/gpu/drm/virtio/virtgpu_object.c","drivers/gpu/drm/virtio/virtgpu_vq.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"93c557e947ef0040004b1ac6a1c1265d79a957e1","status":"affected","version":"a3b815f09bb846255c458c181b8a5b1cc66891b4","versionType":"git"},{"lessThan":"455184dbe9652d01470d3c5cf5edd09a7a673a99","status":"affected","version":"a3b815f09bb846255c458c181b8a5b1cc66891b4","versionType":"git"},{"lessThan":"6a736d2f9d0c6e6217fe7532bc4c50ceca71db78","status":"affected","version":"a3b815f09bb846255c458c181b8a5b1cc66891b4","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/gpu/drm/virtio/virtgpu_drv.h","drivers/gpu/drm/virtio/virtgpu_object.c","drivers/gpu/drm/virtio/virtgpu_vq.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.20"},{"lessThan":"4.20","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.53","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.7","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.53","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.7","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc2","versionStartIncluding":"4.20","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/virtio: use the DMA API for resource backing on Xen\n\nOn a Xen PV domain page addresses bear no relation to the real machine\naddresses the host would have to use to reach it.\nvirtio_ring.c handles this correctly, vring_use_map_api() returns true\nfor any xen_domain() regardless of VIRTIO_F_ACCESS_PLATFORM.\n\nvirtio-gpu makes the same decision independently, but its copy\nlooks only at the feature bit:\n\n\tbool use_dma_api = !virtio_has_dma_quirk(vgdev->vdev);\n\nQEMU does not set iommu_platform on virtio-vga by default, so\nVIRTIO_F_ACCESS_PLATFORM is not negotiated, use_dma_api is false, and\nvirtio_gpu_object_shmem_init() describes the framebuffer's backing pages\nto the host with sg_phys().  Those are guest-physical addresses. In a PV\ndomain they resolve, on the host side, to pages belonging to some other\ndomain, so the host scans out unrelated memory.\n\nMove the decision into virtio_gpu_use_dma_api() and give it the\nxen_domain() check, like vring_use_map_api() has. This\nadditionally enables the dma_sync_sgtable_for_device() calls in\nvirtgpu_vq.c, which are required for correctness whenever swiotlb\nis in play.\n\nReproduced with a Xen 4.21 PV dom0 nested inside QEMU 8.2 with\nvirtio-vga, on both a distro 6.8 kernel and 6.18 LTS. A PVH dom0\nworks fine and doesn't need this fix because it is identity-mapped,\nonly PV dom0s are affected."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The attacker is a local process in the Xen PV dom0. It opens the virtio-gpu render node and calls VIRTGPU_RESOURCE_CREATE, which runs virtio_gpu_object_shmem_init(), and then VIRTGPU_TRANSFER_TO_HOST or TRANSFER_FROM_HOST. No remote peer supplies the bad sg_phys() addresses; the guest driver builds them itself.\nAC:H - The bug only exists on a Xen PV dom0 nested inside QEMU with virtio-vga and without iommu_platform, so VIRTIO_F_ACCESS_PLATFORM is not negotiated. This is a rare deployment the attacker cannot create. The attacker also cannot choose which foreign machine frames the pseudo-physical pfns resolve to.\nPR:L - VIRTGPU_RESOURCE_CREATE, TRANSFER_TO_HOST and TRANSFER_FROM_HOST are all marked DRM_RENDER_ALLOW. Any user with access to /dev/dri/renderD* (render group or a logind seat ACL) can reach them without root.\nUI:N - The attacker creates the resource and issues the transfer ioctls entirely on their own. No other user has to act.\nS:C - virtio_gpu_object_shmem_init() hands the host guest-pseudo-physical addresses, which the host resolves to machine frames owned by other Xen domains or by Xen itself. So a flaw in the dom0 driver affects memory outside that domain's security authority.\nC:H - virtio_gpu_cmd_transfer_to_host_2d/3d make the host copy unrelated machine pages (other domains' memory) into a host resource, which is then scanned out. With virgl, the attacker could plausibly copy that resource into memory they can read back.\nI:H - With virgl, VIRTGPU_TRANSFER_FROM_HOST makes the host write resource data to the wrong backing addresses. Those addresses are machine frames belonging to other domains or the hypervisor, so this is an uncontrolled cross-domain memory write.\nA:H - Host writes into foreign machine frames through the bad backing entries can corrupt Xen or other domains' memory, crashing them. The unsynced swiotlb path (missing dma_sync_sgtable_for_device) also corrupts display data."}]}],"providerMetadata":{"dateUpdated":"2026-09-25T14:42:14.960Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/93c557e947ef0040004b1ac6a1c1265d79a957e1"},{"url":"https://git.kernel.org/stable/c/455184dbe9652d01470d3c5cf5edd09a7a673a99"},{"url":"https://git.kernel.org/stable/c/6a736d2f9d0c6e6217fe7532bc4c50ceca71db78"}],"title":"drm/virtio: use the DMA API for resource backing on Xen","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98156","datePublished":"2026-09-25T10:36:26.409Z","dateReserved":"2026-09-25T10:25:14.320Z","dateUpdated":"2026-09-25T14:42:14.960Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-25 11:17:47","lastModifiedDate":"2026-09-25 15:18:07","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.1,"impactScore":6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98156","Ordinal":"1","Title":"drm/virtio: use the DMA API for resource backing on Xen","CVE":"CVE-2026-98156","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98156","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/virtio: use the DMA API for resource backing on Xen\n\nOn a Xen PV domain page addresses bear no relation to the real machine\naddresses the host would have to use to reach it.\nvirtio_ring.c handles this correctly, vring_use_map_api() returns true\nfor any xen_domain() regardless of VIRTIO_F_ACCESS_PLATFORM.\n\nvirtio-gpu makes the same decision independently, but its copy\nlooks only at the feature bit:\n\n\tbool use_dma_api = !virtio_has_dma_quirk(vgdev->vdev);\n\nQEMU does not set iommu_platform on virtio-vga by default, so\nVIRTIO_F_ACCESS_PLATFORM is not negotiated, use_dma_api is false, and\nvirtio_gpu_object_shmem_init() describes the framebuffer's backing pages\nto the host with sg_phys().  Those are guest-physical addresses. In a PV\ndomain they resolve, on the host side, to pages belonging to some other\ndomain, so the host scans out unrelated memory.\n\nMove the decision into virtio_gpu_use_dma_api() and give it the\nxen_domain() check, like vring_use_map_api() has. This\nadditionally enables the dma_sync_sgtable_for_device() calls in\nvirtgpu_vq.c, which are required for correctness whenever swiotlb\nis in play.\n\nReproduced with a Xen 4.21 PV dom0 nested inside QEMU 8.2 with\nvirtio-vga, on both a distro 6.8 kernel and 6.18 LTS. A PVH dom0\nworks fine and doesn't need this fix because it is identity-mapped,\nonly PV dom0s are affected.","Type":"Description","Title":"drm/virtio: use the DMA API for resource backing on Xen"}]}}}