{"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"}}}}