How severe is CVE-2026-74439?

CVE-2026-74439 has a CVSS score of 9.3/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-74439?

CVE-2026-74439 affects the following packages: Kernel (Linux). Ecosystems affected: Linux.

How do I fix CVE-2026-74439?

Update Kernel to 6.12.97 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-74439 is resolved across your whole dependency graph.

How do I detect CVE-2026-74439 in my Linux dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-74439 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-74439?

O3 pinpoints whether CVE-2026-74439 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-74439 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-74439 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was CVE-2026-74439 published, and has it been updated?

CVE-2026-74439 was published on August 15, 2026 and was last updated on August 18, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐧

🐧 Linux

Not in CISA KEV

CRITICAL severity

CVE-2026-74439

CRITICAL

CVE-2026-74439 is a critical-severity (CVSS 9.3) vulnerability in Kernel. O3 Security confirms whether CVE-2026-74439 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

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

Published

Aug 15, 2026

Updated

Aug 18, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Aug 18, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🐧Kernel

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Linux packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐧Linux	`Kernel`	≥ 6.9.0&&< 6.12.97	6.12.97

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update Kernel to 6.12.97 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-74439 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-74439 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-74439. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 dire

O3 Security · Impact-Aware SCA

Is CVE-2026-74439 in your dependencies?

O3 detects CVE-2026-74439 across Linux dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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