---
cve: "CVE-2026-74310"
severity: "CRITICAL"
cvss: 9.3
epss: "14%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-08-15 06:22:30"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-03T03:51:22+02:00"
---

# CVE-2026-74310

> 9.3 CRITICAL

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 6.1.178
- Kernel ≥ 6.6.145
- Kernel ≥ 6.12.97
- Kernel ≥ 6.18.40
- Kernel ≥ 7.1.5

## Referenzen

- <https://git.kernel.org/stable/c/ea71f873423fb73e66ad88936d6759ac0ad4aa53>
- <https://git.kernel.org/stable/c/6445b945024f4c7675ae5352b2d5885cb1deea71>
- <https://git.kernel.org/stable/c/a9f8a1d2e3ff511eafd4c5462481950c2f4d2b5d>
- <https://git.kernel.org/stable/c/321c73baf54d971ce3771fea275c98a247f7ee35>
- <https://git.kernel.org/stable/c/c069437924663539a93a1e5afe90838d9ccee284>
- <https://git.kernel.org/stable/c/8f6898fe80794f2d7c3d38c1158c806e4074a1c4>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-74310) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_