{"cve":"CVE-2026-64457","nvd":{"published":"2026-07-25T10:17:30.830","modified":"2026-08-17T05:17:50.867","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvirtio_pci: fix vq info pointer lookup via wrong index\n\nUnbinding a virtio balloon device:\n\n    echo virtio0 > /sys/bus/virtio/drivers/virtio_balloon/unbind\n\ntriggers a NULL pointer dereference. The dmesg says:\n\n    BUG: kernel NULL pointer dereference, address: 0000000000000008\n    [...]\n    RIP: 0010:__list_del_entry_valid_or_report+0x5/0xf0\n    Call Trace:\n    <TASK>\n    vp_del_vqs+0x121/0x230\n    remove_common+0x135/0x150\n    virtballoon_remove+0xee/0x100\n    virtio_dev_remove+0x3b/0x80\n    device_release_driver_internal+0x187/0x2c0\n    unbind_store+0xb9/0xe0\n    kernfs_fop_write_iter.llvm.11660790530567441834+0xf6/0x180\n    vfs_write+0x2a9/0x3b0\n    ksys_write+0x5c/0xd0\n    do_syscall_64+0x54/0x230\n    entry_SYSCALL_64_after_hwframe+0x29/0x31\n    [...]\n    </TASK>\n\nThe virtio_balloon device registers 5 queues (inflate, deflate, stats,\nfree_page, reporting) but only the first two are unconditional. The\nstats, free_page and reporting queues are each conditional on their\nrespective feature bits. When any of these features are absent, the\ncorresponding vqs_info entry has name == NULL, creating holes in the\narray.\n\nThe root cause is an indexing mismatch introduced when vq info storage\nwas changed to be passed as an argument. vp_find_vqs_msix() and\nvp_find_vqs_intx() store the info pointer at vp_dev->vqs[i], where 'i'\nis the caller's sparse array index. However, the virtqueue itself gets\nvq->index assigned from queue_idx, a dense index that skips NULL\nentries. When holes exist, 'i' and queue_idx diverge. Later,\nvp_del_vqs() looks up info via vp_dev->vqs[vq->index] using the dense\nindex into the sparsely-populated array, and hits NULL.\n\nFix this by storing info at vp_dev->vqs[queue_idx] instead of\nvp_dev->vqs[i], so the store index matches the lookup index\n(vq->index). Apply the fix to both the MSIX and INTX paths.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/075bc3c779e1ea7294afabdcb7e0a49536959b28","https://git.kernel.org/stable/c/41e6dc1a10036c9f47057033f19af7e52ec464b6","https://git.kernel.org/stable/c/64a4c0befa77bcc01076aec9f93863ffd4ed06b7","https://git.kernel.org/stable/c/f7d380fb525c13bdd114369a1979c80c346e6abc"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:46:40.600842820+00:00"},"epss":{"cve":"CVE-2026-64457","score":0.00175,"percentile":0.07019,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}