vhost/net: complete zerocopy ubufs only once

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74310
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:22:30 UTC
Updated2026-08-17 06:19:25 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 9.3 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.001400000 probability, percentile 0.037990000 (date 2026-08-17)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.3CRITICALCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1CNADECLARED9.3CRITICALCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected bab632d69ee48a106e779b60cc01adfe80a72807 ea71f873423fb73e66ad88936d6759ac0ad4aa53 git Not specified
CNA Linux Linux affected bab632d69ee48a106e779b60cc01adfe80a72807 6445b945024f4c7675ae5352b2d5885cb1deea71 git Not specified
CNA Linux Linux affected bab632d69ee48a106e779b60cc01adfe80a72807 a9f8a1d2e3ff511eafd4c5462481950c2f4d2b5d git Not specified
CNA Linux Linux affected bab632d69ee48a106e779b60cc01adfe80a72807 321c73baf54d971ce3771fea275c98a247f7ee35 git Not specified
CNA Linux Linux affected bab632d69ee48a106e779b60cc01adfe80a72807 c069437924663539a93a1e5afe90838d9ccee284 git Not specified
CNA Linux Linux affected bab632d69ee48a106e779b60cc01adfe80a72807 8f6898fe80794f2d7c3d38c1158c806e4074a1c4 git Not specified
CNA Linux Linux affected 3.1 Not specified
CNA Linux Linux unaffected 3.1 semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.97 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.40 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/321c73baf54d971ce3771fea275c98a247f7ee35 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a9f8a1d2e3ff511eafd4c5462481950c2f4d2b5d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8f6898fe80794f2d7c3d38c1158c806e4074a1c4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c069437924663539a93a1e5afe90838d9ccee284 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ea71f873423fb73e66ad88936d6759ac0ad4aa53 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6445b945024f4c7675ae5352b2d5885cb1deea71 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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