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NVD / CVE Program· CNA Linux

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

CriticalCVSS 9.3 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 37/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.19% (FIRST EPSS).
  • Someone with local access to the system can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 588718101e8449605f1c7e858fecb7cfa701cdab, 6.9, 7fd4077dc92b91b1b844333c0a06bb9e286db10a.

Low priority for now. Upgrade to Linux Linux 588718101e8449605f1c7e858fecb7cfa701cdab, 6.9, 7fd4077dc92b91b1b844333c0a06bb9e286db10a or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published
Aug 15, 2026
Updated
Oct 16, 2026
EPSS
0.1% · 9th percentile
CWE
—

Report tools

JSON

Action score

37

Monitor

Low priority for now.

CVSS
37 / 40 · 9.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Follow CVE-2026-74439

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 333fe86968482ca701c609af590003bcea450e8f, 6.9affected
    • 81e921fd321614c2ad8ac333b041aae1da7a1c6d and later · before e9e83bcfe37dc719182500dd823c03ab57d934f0affected · git
    • 81e921fd321614c2ad8ac333b041aae1da7a1c6d and later · before 588718101e8449605f1c7e858fecb7cfa701cdabaffected · git
    • 81e921fd321614c2ad8ac333b041aae1da7a1c6d and later · before 7fd4077dc92b91b1b844333c0a06bb9e286db10aaffected · git
    • 81e921fd321614c2ad8ac333b041aae1da7a1c6d and later · before f46452c3df7a8d8a5addc0926e76ef19ea7da0a0affected · git
    • 6.8.2 and later · before 6.9affected · semver
    • before 6.9not affected · semver
    • 6.12.97 and later · up to and including 6.12.*not affected · semver
    • 6.18.40 and later · up to and including 6.18.*not affected · semver
    • 7.1.5 and later · up to and including 7.1.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-74432Aug 15, 2026 · rxrpc: Fix leak of released call in recvmsg(MSG_PEEK)
    0Monitor
  • ← EarlierCVE-2026-74436Aug 15, 2026 · rxrpc: serialize kernel accept preallocation with socket teardown
    39Monitor
  • Later →CVE-2026-74441Aug 15, 2026 · usb: typec: ucsi: Fix race condition and ordering in port unregistration
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux588718101e8449605f1c7e858fecb7cfa701cdabVendor (CNA)
Linux Linux6.9Vendor (CNA)
Linux Linux7fd4077dc92b91b1b844333c0a06bb9e286db10aVendor (CNA)
Linux Linuxe9e83bcfe37dc719182500dd823c03ab57d934f0Vendor (CNA)
Linux Linuxf46452c3df7a8d8a5addc0926e76ef19ea7da0a0Vendor (CNA)
debian:linux6.12.100-1 · Debian:13Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Not on record for this CVE: patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records