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NVD / CVE Program· CNA Linux

CVE-2026-45944: iommu/vt-d: Clear Present bit before tearing down context entry

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. Administrator privileges are required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: Linux Linux a922dbafb4a674d958d702038232d09a30daf770, ab4aeab2d630e68be60ccbea3fcf76fa7c281a18, c1e4f1dccbe9d7656d1c6872ebeadb5992d0aaa2; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux a922dbafb4a674d958d702038232d09a30daf770, ab4aeab2d630e68be60ccbea3fcf76fa7c281a18, c1e4f1dccbe9d7656d1c6872ebeadb5992d0aaa2; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes 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 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.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
May 27, 2026
Updated
Oct 21, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 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
7.5
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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-45944

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • 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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.24 and later · before 6.18.14
  • linux linux kernel6.19 and later · before 6.19.4

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

    • 2.6.24affected
    • ba39592764ed20cee09aae5352e603a27bf56b0d and later · before ab4aeab2d630e68be60ccbea3fcf76fa7c281a18affected · git
    • ba39592764ed20cee09aae5352e603a27bf56b0d and later · before c716a59e9977d751e5eb54bcfa6a80124cb5067baffected · git
    • ba39592764ed20cee09aae5352e603a27bf56b0d and later · before d2138abc8f0a7fce4101b7229b43b06811ed083daffected · git
    • ba39592764ed20cee09aae5352e603a27bf56b0d and later · before a922dbafb4a674d958d702038232d09a30daf770affected · git
    • ba39592764ed20cee09aae5352e603a27bf56b0d and later · before c1e4f1dccbe9d7656d1c6872ebeadb5992d0aaa2affected · git
    • before 2.6.24not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver
    • 6.12.97 and later · up to and including 6.12.*not affected · semver
    • 6.18.14 and later · up to and including 6.18.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 6.18.14-16.18.14-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-45942May 27, 2026 · ext4: fix e4b bitmap inconsistency reports
    31Monitor
  • ← EarlierCVE-2026-45943May 27, 2026 · erofs: fix inline data read failure for ztailpacking pclusters
    28Monitor
  • Later →CVE-2026-45945May 27, 2026 · iommu/vt-d: Fix race condition during PASID entry replacement
    35Monitor

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 Linuxa922dbafb4a674d958d702038232d09a30daf770Vendor (CNA)
Linux Linuxab4aeab2d630e68be60ccbea3fcf76fa7c281a18Vendor (CNA)
Linux Linuxc1e4f1dccbe9d7656d1c6872ebeadb5992d0aaa2Vendor (CNA)
Linux Linuxc716a59e9977d751e5eb54bcfa6a80124cb5067bVendor (CNA)
Linux Linuxd2138abc8f0a7fce4101b7229b43b06811ed083dVendor (CNA)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux6.12.100-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package 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).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • Administrator privileges are required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

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
High
Privileges required
High
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:H/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.

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

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

All records