CVE-2026-64034

Guest kernel corruption via DMA double-fetch

Published Jul 19, 2026 · Updated Jul 19, 2026

TOCTOU in the Linux Kernel MANA driver allows attackers controlling a host to corrupt a confidential guest kernel via DMA. The mana_hwc_rx_event_handler function bounds-checks hwc_msg_id in a DMA-coherent response, but mana_hwc_handle_resp re-reads that host-visible field for bitmap testing and pointer arithmetic, allowing the value to change after validation. Exploitation requires a hostile host or hypervisor, an active MANA driver, and posted HWC receive buffers; the resulting out-of-bounds access enables kernel-memory disclosure or corruption and can crash or hang the guest.

CVSS severity9.3
Critical
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TOCTOU in the Linux Kernel MANA driver allows attackers controlling a host to corrupt a confidential guest kernel via DMA. The mana_hwc_rx_event_handler function bounds-checks hwc_msg_id in a DMA-coherent response, but mana_hwc_handle_resp re-reads that host-visible field for bitmap testing and pointer arithmetic, allowing the value to change after validation. Exploitation requires a hostile host or hypervisor, an active MANA driver, and posted HWC receive buffers; the resulting out-of-bounds access enables kernel-memory disclosure or corruption and can crash or hang the guest.

The record

CVE
CVE-2026-64034
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
Unavailable
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.13
  2. Affected versionversion=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <09ec063d87c2dd3fa6f3561361a017bd882e9f37
  3. Affected versionversion=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <35f0f0a2536a4d604b4dbad92c85c4a8fdebb870
  4. Affected versionversion=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <3c4db56ccd13dd020fbf43afabaee74a40ec75e4
  5. Affected versionversion=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <566f42fb67a7ebfed6650e407e5b72e6b3e83bf7
  6. Affected versionversion=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <6180a06bbc99fd9114b8db4be6c4d46e40f046ef
  7. Affected versionversion=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <70ad2dff8d052a85dfef15715b531f38a29108cf
  8. Affected versionversion=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <a201c66edf2ebc6cfdc3813a889ba20fecebfae3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.13; version=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <09ec063d87c2dd3fa6f3561361a017bd882e9f37; version=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <35f0f0a2536a4d604b4dbad92c85c4a8fdebb870; version=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <3c4db56ccd13dd020fbf43afabaee74a40ec75e4; version=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <566f42fb67a7ebfed6650e407e5b72e6b3e83bf7; version=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <6180a06bbc99fd9114b8db4be6c4d46e40f046ef; version=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <70ad2dff8d052a85dfef15715b531f38a29108cf; version=ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f <a201c66edf2ebc6cfdc3813a889ba20fecebfae3

Published CVSS scores

9.3Linux kernel CNACVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

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