{"apiVersion":"1.0","identifier":"CVE-2026-74310","description":"In the Linux kernel, the following vulnerability has been resolved: vhost/net: complete zerocopy ubufs only once vhost-net initializes one ubuf_info per outstanding zerocopy TX descriptor and hands it to the backend socket. The networking stack may then clone a zerocopy skb before all skb references are released. For example, batman-adv fragmentation reaches skb_split(), which calls skb_zerocopy_clone() and increments the same ubuf_info refcount. vhost_zerocopy_complete() currently treats every ubuf callback as a completed vhost descriptor. It dereferences ubuf->ctx, writes the descriptor completion state, and drops the vhost_net_ubuf_ref even when the callback only releases a cloned skb reference. A backend reset can therefore wait for and free the vhost_net_ubuf_ref while another cloned skb still carries the same ubuf_info. A later completion then dereferences the freed ubufs pointer. KASAN reports the stale completion as: BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x1d7/0x1f0 BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x101/0x1f0 vhost_zerocopy_complete skb_copy_ubufs __dev_forward_skb2 veth_xmit The freed object was allocated from vhost_net_ioctl() while setting the backend and freed through kfree_rcu()/kvfree_rcu_bulk after backend removal, while delayed skb completion still reached vhost_zerocopy_complete(). Honor the generic ubuf_info refcount before touching vhost state, and run the vhost descriptor completion only for the final ubuf reference. This matches the msg_zerocopy_complete() ownership rule for cloned zerocopy skbs.","publishedAt":"2026-08-15T06:22:30","lastModifiedAt":"2026-08-17T06:19:25","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74310","cvssScore":9.3,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","epssProbability":0.00138,"riskScore":0.94,"affectedProduct":"Linux kernel","affectedVersions":"unknown","vulnerabilityType":"Kernel","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-74310","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-74310","en":"https://www.redsauce.net/en/cves/CVE-2026-74310","fr":"https://www.redsauce.net/fr/cves/CVE-2026-74310","pt":"https://www.redsauce.net/pt/cves/CVE-2026-74310","de":"https://www.redsauce.net/de/cves/CVE-2026-74310","sk":"https://www.redsauce.net/sk/cves/CVE-2026-74310","el":"https://www.redsauce.net/el/cves/CVE-2026-74310"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-74310"}}