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CVE-2026-74439— iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry

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 6.8.2版本至6.9版本存在安全漏洞，该漏洞源于在拆除可扩展模式上下文条目时未先清除Present位，可能导致硬件获取撕裂的条目并访问已释放内存，引发不可预测行为或虚假故障。

CVSS 9.3 · Critical EPSS 0.20% · P9

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 81e921fd321614c2ad8ac333b041aae1da7a1c6d< e9e83bcfe37dc719182500dd823c03ab57d934f0 affected
81e921fd321614c2ad8ac333b041aae1da7a1c6d< 588718101e8449605f1c7e858fecb7cfa701cdab affected
81e921fd321614c2ad8ac333b041aae1da7a1c6d< 7fd4077dc92b91b1b844333c0a06bb9e286db10a affected
81e921fd321614c2ad8ac333b041aae1da7a1c6d< f46452c3df7a8d8a5addc0926e76ef19ea7da0a0 affected
333fe86968482ca701c609af590003bcea450e8f affected
6.8.2< 6.9 affected
6.9 affected
< 6.9 unaffected
… +4 more rows
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I. Basic Information for CVE-2026-74439

Vulnerability Information
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Vulnerability Title
iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry device_pasid_table_teardown() zeroes the 128-bit scalable-mode context entry with context_clear_entry() while the Present bit is still set. This creates a window where the hardware can fetch a torn entry, with some fields already zeroed while Present is still set, leading to unpredictable behavior or spurious faults. The context-cache invalidation is issued only after the entry has been zeroed, and intel_pasid_free_table() then frees the PASID directory pages, so the IOMMU can keep walking a stale Present=1 entry that points at freed memory. While x86 provides strong write ordering, the compiler may reorder the two 64-bit writes to the entry, and the hardware fetch is not guaranteed to be atomic with respect to multiple CPU writes. Commit c1e4f1dccbe9d ("iommu/vt-d: Clear Present bit before tearing down context entry") fixed this exact pattern in domain_context_clear_one() and the copied-context path, but device_pasid_table_teardown() was not converted. Align it with the "Guidance to Software for Invalidations" in the VT-d spec, Section 6.5.3.3, using the same ownership handshake as the sibling fix: clear only the Present bit, flush it to the IOMMU, perform the context-cache invalidation, and only then zero the rest of the entry.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/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 6.8.2版本至6.9版本存在安全漏洞，该漏洞源于在拆除可扩展模式上下文条目时未先清除Present位，可能导致硬件获取撕裂的条目并访问已释放内存，引发不可预测行为或虚假故障。
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 81e921fd321614c2ad8ac333b041aae1da7a1c6d ~ e9e83bcfe37dc719182500dd823c03ab57d934f0 -
Linux Linux 6.9 -

II. Public POCs for CVE-2026-74439

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III. Intelligence Information for CVE-2026-74439

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Patches & Fixes for CVE-2026-74439 (4)

Same Patch Batch · Linux · 2026-08-15 · 844 CVEs total

CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72084 9.8 CRITICAL scsi: target: Bound PR-OUT TransportID parsing to the received buffer
CVE-2026-74480 9.8 CRITICAL net: bridge: stop fast-leave after deleting a port group
CVE-2026-72083 9.8 CRITICAL scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE
CVE-2026-72248 9.8 CRITICAL netfilter: flowtable: support IPIP tunnel with direct xmit
CVE-2026-72249 9.8 CRITICAL netfilter: flowtable: use dst in this direction when pushing IPIP header
CVE-2026-72251 9.8 CRITICAL netfilter: nf_nat_sip: reload possible stale data pointer
CVE-2026-74493 9.8 CRITICAL net/smc: fix socket use-after-free during link group termination
CVE-2026-74495 9.8 CRITICAL igbvf: Fix leak in TX DMA error cleanup
CVE-2026-72191 9.8 CRITICAL ntfs3: validate split-point offset in indx_insert_into_buffer
CVE-2026-74398 9.8 CRITICAL ipv6: addrconf: bail out of dad_failure when state is no longer POSTDAD
CVE-2026-74315 9.8 CRITICAL lockd: Avoid hashing uninitialized bytes in nlm4svc_lookup_file()
CVE-2026-72046 9.8 CRITICAL gve: fix header buffer corruption with header-split and HW-GRO

Showing top 20 of 844 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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