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TI-2026-33669 Aliases CVE-2026-45944GHSA-xp3w-6f4f-gvg7

iommu/vt-d: Clear Present bit before tearing down context entry

Priority LOW 34CWE-362Published · Updated

Key facts

Attack vector
Local
Privileges required
High
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 3 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00124 2nd percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.1.191, 6.6.160, 6.12.97 +3Red Hat: 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux2.6.24 and later6.1.191, 6.6.160, 6.12.97, 6.18.14, 6.19.4, 7.0Patch availableCNA
  • Linux VendorLinux Affected 2.6.24 and later Fixed in 6.1.191, 6.6.160, 6.12.97, 6.18.14, 6.19.4, 7.0 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*2.6.24 to before 6.18.14; 6.19 to before 6.19.4VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 2.6.24 to before 6.18.14; 6.19 to before 6.19.4 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.97, 6.18.14, 6.19.4, 7.0

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix planned: Out of support scope
Not affected: 2 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-45944
  2. 2026-10-03 Alias added: GHSA-xp3w-6f4f-gvg7
  3. 2026-10-16 CISA SSVC decision points changed
  4. 2026-10-19 Weakness changed · CISA ADP
  5. 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@ab4aeab2d630e68be60ccbea3fcf76fa7c281a18 · CNA
  6. 2026-10-21 1 new reference · CNA
  7. 2026-10-29 Affected versions changed · Red Hat
  8. 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@61fa8546e39331103d6ce01575699c577d83e000 · CNA
  9. 2026-10-30 1 new reference · CNA

References

Patch 3

Other 3

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences