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CVE-2026-74356— vhost: fix vhost_get_avail_idx for a non empty ring

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 5.18版本存在安全漏洞，该漏洞源于vhost_get_avail_idx函数返回值错误，可能导致主机活锁。

CVSS 7.4 · High EPSS 0.24% · P15

Possible ATT&CK Techniques 1 AI

T1055 · Process Injection

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux d3bb267bbdcba199568f1325743d9d501dea0560< e115471008111f894c6528d9ab2ce7d0ce306f35 affected
d3bb267bbdcba199568f1325743d9d501dea0560< 7f229d27bf27c7e589eca690d8612763a7a4801f affected
d3bb267bbdcba199568f1325743d9d501dea0560< a9326b652bc7acd748d7a1143573845c7924d847 affected
d3bb267bbdcba199568f1325743d9d501dea0560< 09861858a68342f851f71c669ac0f69865c32151 affected
5.18 affected
< 5.18 unaffected
6.12.97≤ 6.12.* unaffected
6.18.40≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-74356

Vulnerability Information
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Vulnerability Title
vhost: fix vhost_get_avail_idx for a non empty ring
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: vhost: fix vhost_get_avail_idx for a non empty ring vhost_get_avail_idx is supposed to report whether it has updated vq->avail_idx. Instead, it returns whether all entries have been consumed, which is usually the same. But not always - in drivers/vhost/net.c and when mergeable buffers have been enabled, the driver checks whether the combined entries are big enough to store an incoming packet. If not, the driver re-enables notifications with available entries still in the ring. The incorrect return value from vhost_get_avail_idx propagates through vhost_enable_notify and causes the host to livelock if the guest is not making progress, as vhost will immediately disable notifications and retry using the available entries. This goes back to commit d3bb267bbdcb ("vhost: cache avail index in vhost_enable_notify()") which changed vhost_enable_notify() to compare the freshly read avail index against vq->last_avail_idx instead of the previously cached vq->avail_idx. Commit 7ad472397667 ("vhost: move smp_rmb() into vhost_get_avail_idx()") then carried over the same comparison when refactoring vhost_enable_notify() to call the unified vhost_get_avail_idx(). The obvious fix is to make vhost_get_avail_idx do what the comment says it does and report whether new entries have been added.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 5.18版本存在安全漏洞，该漏洞源于vhost_get_avail_idx函数返回值错误，可能导致主机活锁。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux d3bb267bbdcba199568f1325743d9d501dea0560 ~ e115471008111f894c6528d9ab2ce7d0ce306f35 -
Linux Linux 5.18 -

II. Public POCs for CVE-2026-74356

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III. Intelligence Information for CVE-2026-74356

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Patches & Fixes for CVE-2026-74356 (4)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-74376 9.8 CRITICAL md/raid10: reset read_slot when reusing r10bio for discard
CVE-2026-72234 9.8 CRITICAL batman-adv: access unicast_ttvn skb->data only after skb realloc
CVE-2026-72339 9.8 CRITICAL qede: fix off-by-one in BD ring consumption on build_skb failure
CVE-2026-74255 9.8 CRITICAL tipc: fix UAF in tipc_l2_send_msg()
CVE-2026-72064 9.8 CRITICAL net: mana: Sync page pool RX frags for CPU
CVE-2026-72065 9.8 CRITICAL net: mana: Validate the packet length reported by the NIC
CVE-2026-72217 9.8 CRITICAL SUNRPC: Bound-check xdr_buf_to_bvec() stores before writing
CVE-2026-74473 9.8 CRITICAL vxlan: use pskb_network_may_pull() in route_shortcircuit()
CVE-2026-72323 9.8 CRITICAL ipv4: igmp: Fix potential UAF in igmp_gq_start_timer()
CVE-2026-74495 9.8 CRITICAL igbvf: Fix leak in TX DMA error cleanup
CVE-2026-72463 9.8 CRITICAL xfrm: Fix dev use-after-free in xfrm async resumption
CVE-2026-72069 9.8 CRITICAL locking/rt: Fix the incorrect RCU protection in rt_spin_unlock()

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-74356

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