{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63970", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.024Z", "datePublished": "2026-07-19T14:55:57.067Z", "dateUpdated": "2026-08-05T12:37:41.706Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:37:41.706Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/virtio: bind uarg before filling zerocopy skb\n\nvirtio_transport_send_pkt_info() allocates or reuses the zerocopy uarg\nbefore entering the send loop, but virtio_transport_alloc_skb() still\nfills the skb before it inherits that uarg. When fixed-buffer vectored\nzerocopy hits MAX_SKB_FRAGS, io_sg_from_iter() may partially attach\nmanaged frags and return -EMSGSIZE. The rollback path call kfree_skb()\nto free an skb that carries SKBFL_MANAGED_FRAG_REFS but no uarg, so\nskb_release_data() falls through to ordinary frag unref.\n\nPass the uarg into virtio_transport_alloc_skb() and bind it immediately\nbefore virtio_transport_fill_skb(). This keeps control or no-payload skbs\nuntouched while ensuring success and rollback share one lifetime rule." } ], "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 bug is reached only via local AF_VSOCK transmission (syscall/io_uring send on a connected virtio vsock socket), not by processing remote network packets. Per kernel CVSS guidance, vsock is Local.\nAC:L - An attacker fully controls the trigger: SO_ZEROCOPY, io_uring IORING_OP_SEND_ZC with IORING_RECVSEND_FIXED_BUF and a vectored iov exceeding MAX_SKB_FRAGS (17), causing io_sg_from_iter() to return -EMSGSIZE on a deterministic error rollback path.\nPR:L - Exploitation requires only an unprivileged local process that can open a vsock connection and use io_uring zerocopy send; no CAP_NET_ADMIN or real root is needed beyond ordinary local user access in a virtio-vsock environment (KVM/Firecracker/cloud microVMs).\nUI:N - No victim interaction is required; the attacker triggers the bug directly through their own socket send/io_uring operation.\nS:U - Impact is kernel memory corruption and privilege escalation within the same security domain where the send occurs (guest kernel or host kernel). It is not a cross-boundary VM escape on the receive path; the flaw is in the sender's local skb teardown.\nC:H - Incorrect __skb_frag_unref() on SKBFL_MANAGED_FRAG_REFS pages without a bound uarg corrupts refcount/lifetime of io_uring registered buffer pages, yielding use-after-free and arbitrary kernel memory read primitives.\nI:H - The refcount corruption is a memory-safety bug in kernel heap/page management that can be leveraged for arbitrary write and control-flow hijacking, not merely a bounded data change.\nA:H - The erroneous frag unref on managed zerocopy pages can cause immediate kernel oops/panic from refcount underflow or use-after-free during skb teardown, independent of full exploitation." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/vmw_vsock/virtio_transport_common.c" ], "versions": [ { "version": "581512a6dc939ef122e49336626ae159f3b8a345", "lessThan": "72194f65050958e4c8e069adb6c5d89ef81ca197", "status": "affected", "versionType": "git" }, { "version": "581512a6dc939ef122e49336626ae159f3b8a345", "lessThan": "b62e2b2b4a50953ca952f3cd3f77dd62dc50fd5d", "status": "affected", "versionType": "git" }, { "version": "581512a6dc939ef122e49336626ae159f3b8a345", "lessThan": "5d317573f1d48e76cce5fb6250452b6e4102e0fb", "status": "affected", "versionType": "git" }, { "version": "581512a6dc939ef122e49336626ae159f3b8a345", "lessThan": "1e584c304cfb94a759417130b1fc6d30b30c4cce", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/vmw_vsock/virtio_transport_common.c" ], "versions": [ { "version": "6.7", "status": "affected" }, { "version": "0", "lessThan": "6.7", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "6.7", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.18.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/72194f65050958e4c8e069adb6c5d89ef81ca197" }, { "url": "https://git.kernel.org/stable/c/b62e2b2b4a50953ca952f3cd3f77dd62dc50fd5d" }, { "url": "https://git.kernel.org/stable/c/5d317573f1d48e76cce5fb6250452b6e4102e0fb" }, { "url": "https://git.kernel.org/stable/c/1e584c304cfb94a759417130b1fc6d30b30c4cce" } ], "title": "vsock/virtio: bind uarg before filling zerocopy skb", "x_generator": { "engine": "bippy-1.2.0" } } } }