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NVD / CVE Program· CNA Linux

CVE-2026-68329: iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()

Noroxi assessment

Priority: Monitor (action score 35/100)

  • 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. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 02f8cefa2ad95ea3754f0cfd6fbae7f866202ccb, 1e75a8255f11c81fb07e81e5029cfd75804350a0, 82c9a749d44efaaa1a1c781f8a6cf1747718f228; azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 6.6.150.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 02f8cefa2ad95ea3754f0cfd6fbae7f866202ccb, 1e75a8255f11c81fb07e81e5029cfd75804350a0, 82c9a749d44efaaa1a1c781f8a6cf1747718f228; azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 6.6.150.1-1 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/amd: Wait for completion instead of returning early in iommu_completion_wait() need_sync is a per-IOMMU flag shared by all domains and devices behind that IOMMU. It is set whenever a command is queued with sync == true and cleared when a completion-wait (CWAIT) command is queued. However, a cleared need_sync only means that a covering CWAIT has been queued, not that all previously queued commands have actually completed in hardware. iommu_completion_wait() read need_sync locklessly and returned early when it was false. This breaks the "block until all previously queued commands have completed" contract in a multi-CPU scenario: CPU2: queue inv-B => need_sync = true CPU1: queue CWAIT(N); need_sync = false; then wait_on_sem(N) CPU2: read need_sync == false => return 0 (no wait!) CPU2 returns without waiting for any sequence number even though its inv-B may not have completed yet (CWAIT(N), queued after inv-B, has not been signaled). CPU2 then proceeds to, for example, free page-table pages while the IOMMU can still walk stale translations, opening a use-after-free window. This is a logical race in the meaning of the flag, not a memory-visibility issue, so barriers alone do not help. Fix it without losing the optimization of avoiding redundant CWAIT commands: take iommu->lock before testing need_sync, and when it is false do not return early but wait for the last allocated sequence number (cmd_sem_val). Since need_sync == false implies no sync command was queued after the last CWAIT, that CWAIT is FIFO-ordered after every not-yet-completed command, so waiting for its sequence number guarantees all prior commands (possibly queued by another CPU) have completed. The common path with pending work is unchanged and no extra hardware command is issued.

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Aug 10, 2026
Updated
Oct 30, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 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
8.8
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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  • 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

    • 3.0affected
    • 815b33fdc279d34ab40a8bfe1866623a4cc5669b and later · before 82c9a749d44efaaa1a1c781f8a6cf1747718f228affected · git
    • 815b33fdc279d34ab40a8bfe1866623a4cc5669b and later · before ab7faf5a172ebfdc423ebb3eea4d472740de82f9affected · git
    • 815b33fdc279d34ab40a8bfe1866623a4cc5669b and later · before 93494bd446396c257fb589f59894577e96e406e2affected · git
    • 815b33fdc279d34ab40a8bfe1866623a4cc5669b and later · before d053eb7e09e10cbdca3fca8b35c1017d438091b2affected · git
    • 815b33fdc279d34ab40a8bfe1866623a4cc5669b and later · before 02f8cefa2ad95ea3754f0cfd6fbae7f866202ccbaffected · git
    • 815b33fdc279d34ab40a8bfe1866623a4cc5669b and later · before 1e75a8255f11c81fb07e81e5029cfd75804350a0affected · git
    • before 3.0not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.148 and later · up to and including 6.6.*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 6.12.101-1~deb12u16.12.101-1~deb12u1
Debian:13linuxbefore 6.12.101-16.12.101-1
Debian:14linuxbefore 7.1.6-17.1.6-1

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-2026-68326Aug 10, 2026 · wifi: mwifiex: bound uAP association event IEs to the event buffer
    35Monitor
  • ← EarlierCVE-2026-68328Aug 10, 2026 · nfp: Check resource mutex allocation
    0Monitor
  • Later →CVE-2026-68335Aug 10, 2026 · rds: drop incoming messages that cross network namespace boundaries
    31Monitor

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 Linux02f8cefa2ad95ea3754f0cfd6fbae7f866202ccbVendor (CNA)
Linux Linux1e75a8255f11c81fb07e81e5029cfd75804350a0Vendor (CNA)
Linux Linux82c9a749d44efaaa1a1c781f8a6cf1747718f228Vendor (CNA)
Linux Linux93494bd446396c257fb589f59894577e96e406e2Vendor (CNA)
Linux Linuxab7faf5a172ebfdc423ebb3eea4d472740de82f9Vendor (CNA)
Linux Linuxd053eb7e09e10cbdca3fca8b35c1017d438091b2Vendor (CNA)
azl3 kernel 6.6.143.1-1 on Azure Linux 3.06.6.150.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.12.101-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.101-1~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.

  • CVE-2026-720645 days apartnet: mana: Sync page pool RX frags for CPU
    39Monitor
  • CVE-2026-6397822 days apartnet/handshake: Drain pending requests at net namespace exit
    39Monitor
  • CVE-2026-645616 days apartKVM: x86: Check for invalid/obsolete root *after* making MMU pages available
    35Monitor
  • CVE-2026-681430 days apartnet: slip: serialize receive against buffer reallocation
    31Monitor
  • CVE-2026-681890 days apartBluetooth: hci_sync: Protect UUID list traversal
    31Monitor
  • CVE-2026-683840 days apartdrm/xe/vf: Fix VF CCS attach/detach race with in-flight BO moves
    31Monitor

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.
  • A low-privileged account is enough.
  • 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
Low
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:L/PR:L/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

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Change log

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

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

References

Show all references (5 more)

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

All records