{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74310","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-15T05:44:03.883Z","datePublished":"2026-08-15T05:58:10.043Z","dateUpdated":"2026-08-17T05:45:42.723Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T05:45:42.723Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nvhost/net: complete zerocopy ubufs only once\n\nvhost-net initializes one ubuf_info per outstanding zerocopy TX\ndescriptor and hands it to the backend socket.  The networking stack may\nthen clone a zerocopy skb before all skb references are released.  For\nexample, batman-adv fragmentation reaches skb_split(), which calls\nskb_zerocopy_clone() and increments the same ubuf_info refcount.\n\nvhost_zerocopy_complete() currently treats every ubuf callback as a\ncompleted vhost descriptor.  It dereferences ubuf->ctx, writes the\ndescriptor completion state, and drops the vhost_net_ubuf_ref even when\nthe callback only releases a cloned skb reference.  A backend reset can\ntherefore wait for and free the vhost_net_ubuf_ref while another cloned\nskb still carries the same ubuf_info.  A later completion then\ndereferences the freed ubufs pointer.\n\nKASAN reports the stale completion as:\n\n  BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x1d7/0x1f0\n  BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x101/0x1f0\n  vhost_zerocopy_complete\n  skb_copy_ubufs\n  __dev_forward_skb2\n  veth_xmit\n\nThe freed object was allocated from vhost_net_ioctl() while setting the\nbackend and freed through kfree_rcu()/kvfree_rcu_bulk after backend\nremoval, while delayed skb completion still reached\nvhost_zerocopy_complete().\n\nHonor the generic ubuf_info refcount before touching vhost state, and run\nthe vhost descriptor completion only for the final ubuf reference.  This\nmatches the msg_zerocopy_complete() ownership rule for cloned zerocopy\nskbs."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","baseScore":9.3,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:L - The bug is only reachable on the vhost-net TX zerocopy path via /dev/vhost-net ioctls or virtio-net TX descriptors handled by the host vhost worker; remote wire packets do not carry vhost ubuf_info state, so no network-facing host protocol reaches vhost_zerocopy_complete().\nAC:L - Once experimental_zcopytx is enabled, an attacker can reliably send >=256-byte zerocopy TX frames through a tap/veth backend so skb_zerocopy_clone/skb_copy_ubufs fires, then force backend teardown via VHOST_NET_SET_BACKEND or VM stop/migration while cloned completions remain pending.\nPR:N - A malicious KVM guest on a host using vhost-net needs no host root, capabilities, or /dev/vhost-net access—only control of virtio TX descriptors and normal VM networking; a host-side attacker can also open /dev/vhost-net with only device-node permissions because drivers/vhost performs no capable() checks.\nUI:N - No victim user interaction is required beyond standard VM or vhost-net operation; the attacker directly drives virtio TX traffic, optional veth forwarding that clones zerocopy skbs, and backend reset/teardown that frees vhost_net_ubuf_ref while stale ubuf completions are still outstanding.\nS:C - In the standard KVM deployment, vhost-net is host-kernel code enforcing the guest NIC boundary; the slab use-after-free in vhost_zerocopy_complete executes in host context from guest-supplied zerocopy TX, corrupting host vhost/virtqueue state outside the guest security authority.\nC:H - This is a slab use-after-free: after premature completion frees vhost_net_ubuf_ref, a later skb_zcopy_clear callback dereferences freed ubuf->ctx/ubufs memory in vhost_zerocopy_complete, giving attacker-influenced UAF primitives suitable for arbitrary kernel memory disclosure.\nI:H - The stale completion writes vq->heads[ubuf->desc].len and decrements vhost_net_ubuf_ref on freed structures; UAF heap corruption of this class is leveragable into arbitrary write and host control-flow hijacking, including potential VM-to-host privilege escalation.\nA:H - KASAN reports slab-use-after-free in vhost_zerocopy_complete during skb_copy_ubufs/veth_xmit completion; this readily causes host kernel oops or panic and can be retriggered from a virtio guest TX loop or repeated backend resets until the host or hypervisor is unavailable."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/vhost/net.c"],"versions":[{"version":"bab632d69ee48a106e779b60cc01adfe80a72807","lessThan":"ea71f873423fb73e66ad88936d6759ac0ad4aa53","status":"affected","versionType":"git"},{"version":"bab632d69ee48a106e779b60cc01adfe80a72807","lessThan":"6445b945024f4c7675ae5352b2d5885cb1deea71","status":"affected","versionType":"git"},{"version":"bab632d69ee48a106e779b60cc01adfe80a72807","lessThan":"a9f8a1d2e3ff511eafd4c5462481950c2f4d2b5d","status":"affected","versionType":"git"},{"version":"bab632d69ee48a106e779b60cc01adfe80a72807","lessThan":"321c73baf54d971ce3771fea275c98a247f7ee35","status":"affected","versionType":"git"},{"version":"bab632d69ee48a106e779b60cc01adfe80a72807","lessThan":"c069437924663539a93a1e5afe90838d9ccee284","status":"affected","versionType":"git"},{"version":"bab632d69ee48a106e779b60cc01adfe80a72807","lessThan":"8f6898fe80794f2d7c3d38c1158c806e4074a1c4","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/vhost/net.c"],"versions":[{"version":"3.1","status":"affected"},{"version":"0","lessThan":"3.1","status":"unaffected","versionType":"semver"},{"version":"6.1.178","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.145","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.97","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.40","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.5","lessThanOrEqual":"7.1.*","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":"3.1","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.1","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.1","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.1","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.1","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.1","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/ea71f873423fb73e66ad88936d6759ac0ad4aa53"},{"url":"https://git.kernel.org/stable/c/6445b945024f4c7675ae5352b2d5885cb1deea71"},{"url":"https://git.kernel.org/stable/c/a9f8a1d2e3ff511eafd4c5462481950c2f4d2b5d"},{"url":"https://git.kernel.org/stable/c/321c73baf54d971ce3771fea275c98a247f7ee35"},{"url":"https://git.kernel.org/stable/c/c069437924663539a93a1e5afe90838d9ccee284"},{"url":"https://git.kernel.org/stable/c/8f6898fe80794f2d7c3d38c1158c806e4074a1c4"}],"title":"vhost/net: complete zerocopy ubufs only once","x_generator":{"engine":"bippy-1.2.0"}}}}