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CVE-2026-45944— iommu/vt-d: Clear Present bit before tearing down 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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于iommu/vt-d驱动在拆除上下文条目时未先清除Present位，可能导致硬件获取撕裂条目并引发不可预测行为或虚假故障。

CVSS 7.5 · High EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux ba39592764ed20cee09aae5352e603a27bf56b0d< c716a59e9977d751e5eb54bcfa6a80124cb5067b affected
ba39592764ed20cee09aae5352e603a27bf56b0d< d2138abc8f0a7fce4101b7229b43b06811ed083d affected
ba39592764ed20cee09aae5352e603a27bf56b0d< a922dbafb4a674d958d702038232d09a30daf770 affected
ba39592764ed20cee09aae5352e603a27bf56b0d< c1e4f1dccbe9d7656d1c6872ebeadb5992d0aaa2 affected
2.6.24 affected
< 2.6.24 unaffected
6.12.97≤ 6.12.* unaffected
6.18.14≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-45944

Vulnerability Information
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Vulnerability Title
iommu/vt-d: Clear Present bit before tearing down 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 context entry When tearing down a context entry, the current implementation zeros the entire 128-bit entry using multiple 64-bit writes. This creates a window where the hardware can fetch a "torn" entry — where some fields are already zeroed while the 'Present' bit is still set — leading to unpredictable behavior or spurious faults. While x86 provides strong write ordering, the compiler may reorder writes to the two 64-bit halves of the context entry. Even without compiler reordering, the hardware fetch is not guaranteed to be atomic with respect to multiple CPU writes. Align with the "Guidance to Software for Invalidations" in the VT-d spec (Section 6.5.3.3) by implementing the recommended ownership handshake: 1. Clear only the 'Present' (P) bit of the context entry first to signal the transition of ownership from hardware to software. 2. Use dma_wmb() to ensure the cleared bit is visible to the IOMMU. 3. Perform the required cache and context-cache invalidation to ensure hardware no longer has cached references to the entry. 4. Fully zero out the entry only after the invalidation is complete. Also, add a dma_wmb() to context_set_present() to ensure the entry is fully initialized before the 'Present' bit becomes visible.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:H/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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于iommu/vt-d驱动在拆除上下文条目时未先清除Present位，可能导致硬件获取撕裂条目并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 ba39592764ed20cee09aae5352e603a27bf56b0d ~ c716a59e9977d751e5eb54bcfa6a80124cb5067b -
Linux Linux 2.6.24 -

II. Public POCs for CVE-2026-45944

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III. Intelligence Information for CVE-2026-45944

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Patches & Fixes for CVE-2026-45944 (4)

Same Patch Batch · Linux · 2026-05-27 · 275 CVEs total

CVE-2026-45898 9.8 CRITICAL RDMA/iwcm: Fix workqueue list corruption by removing work_list
CVE-2026-46039 9.8 CRITICAL rxgk: Fix potential integer overflow in length check
CVE-2026-45988 9.8 CRITICAL rxrpc: Fix re-decryption of RESPONSE packets
CVE-2026-45972 9.8 CRITICAL smb: client: fix potential UAF and double free in smb2_open_file()
CVE-2026-46043 9.1 CRITICAL RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv
CVE-2026-45945 8.8 HIGH iommu/vt-d: Fix race condition during PASID entry replacement
CVE-2026-46056 8.8 HIGH Bluetooth: hci_event: fix potential UAF in SSP passkey handlers
CVE-2026-45843 8.2 HIGH slip: bound decode() reads against the compressed packet length
CVE-2026-46037 8.2 HIGH ipv4: icmp: validate reply type before using icmp_pointers
CVE-2025-71311 8.2 HIGH fs/ntfs3: Initialize new folios before use
CVE-2026-46010 8.1 HIGH rxrpc: Fix error handling in rxgk_extract_token()
CVE-2026-46099 8.1 HIGH net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
CVE-2026-46076 7.9 HIGH KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1
CVE-2026-45931 7.8 HIGH accel/amdxdna: Hold mm structure across iommu_sva_unbind_device()
CVE-2026-45951 7.8 HIGH bpf: Fix a potential use-after-free of BTF object
CVE-2026-45935 7.8 HIGH fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot
CVE-2026-45933 7.8 HIGH bpf: Preserve id of register in sync_linked_regs()
CVE-2026-45984 7.8 HIGH gfs2: Fix use-after-free in iomap inline data write path
CVE-2026-45862 7.8 HIGH iommu/vt-d: Flush cache for PASID table before using it
CVE-2026-45861 7.8 HIGH gfs2: Fix slab-use-after-free in qd_put

Showing top 20 of 275 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-45944

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