{"id":"CVE-2026-74310","title":"vhost/net: complete zerocopy ubufs only once","summary":"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 networ…","severity":"critical","cvss":9.3,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < ea71f873423fb73e66ad88936d6759ac0ad4aa53","Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < 6445b945024f4c7675ae5352b2d5885cb1deea71","Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < a9f8a1d2e3ff511eafd4c5462481950c2f4d2b5d","Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < 321c73baf54d971ce3771fea275c98a247f7ee35","Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < c069437924663539a93a1e5afe90838d9ccee284","Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < 8f6898fe80794f2d7c3d38c1158c806e4074a1c4","Linux 3.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:52:56.702664Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:32.036Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74310","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"}],"tags":["cve.org"],"epss":0.0019,"epssPercentile":0.08112,"ingestedAt":"2026-10-16T19:46:24.381Z","slug":"CVE-2026-74310","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < ea71f873423fb73e66ad88936d6759ac0ad4aa53`\n- `Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < 6445b945024f4c7675ae5352b2d5885cb1deea71`\n- `Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < a9f8a1d2e3ff511eafd4c5462481950c2f4d2b5d`\n- `Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < 321c73baf54d971ce3771fea275c98a247f7ee35`\n- `Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < c069437924663539a93a1e5afe90838d9ccee284`\n- `Linux >= bab632d69ee48a106e779b60cc01adfe80a72807 < 8f6898fe80794f2d7c3d38c1158c806e4074a1c4`\n- `Linux 3.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":51,"depthScoreParts":{"impact":51.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}