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Review reviewCritical

CVE-2026-64034

Linux

In the Linux kernel, the following vulnerability has been resolved: net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from DMA-coherent memory and bounds-checked, then mana_hwc_handle_resp() re-reads the same field from the same DMA buffer for test_bit() and pointer arithmetic. DMA-coherent memory is mapped uncacheable on x86 and is shared, unencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes directly to host-visible memory. A H/W can modify the value between the check and the use, bypassing the bo...

CVSS
9.3
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.20
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 9.3

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from DMA-coherent memory and bounds-checked, then mana_hwc_handle_resp() re-reads the same field from the same DMA buffer for test_bit() and pointer arithmetic. DMA-coherent memory is mapped uncacheable on x86 and is shared, unencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes directly to host-visible memory. A H/W can modify the value between the check and the use, bypassing the bo...

Affected product and versions

Product
Linux
Affected versions
>= ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f < a201c66edf2ebc6cfdc3813a889ba20fecebfae3, >= ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f < 70ad2dff8d052a85dfef15715b531f38a29108cf, >= ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f < 566f42fb67a7ebfed6650e407e5b72e6b3e83bf7, >= ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f < 6180a06bbc99fd9114b8db4be6c4d46e40f046ef, >= ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f < 09ec063d87c2dd3fa6f3561361a017bd882e9f37, >= ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f < 3c4db56ccd13dd020fbf43afabaee74a40ec75e4, >= ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f < 35f0f0a2536a4d604b4dbad92c85c4a8fdebb870, >= 5.13
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CWE
Not available
CVE-2026-64034 — Linux | SECUFOCUS NOW