CVE-2026-64034
net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer
Description
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 bounds validation. Fix this by reading hwc_msg_id exactly once using READ_ONCE() into a stack-local variable in mana_hwc_rx_event_handler(), and passing the validated value as a parameter to mana_hwc_handle_resp().
INFO
Published Date :
July 19, 2026, 4:17 p.m.
Last Modified :
July 20, 2026, 3:17 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2026-64034
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Read the message ID exactly once into a local variable.
- Pass the validated message ID as a parameter.
- Ensure the hardware cannot modify data between checks.
- Apply the kernel patch to fix the TOCTOU flaw.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-64034.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-64034 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-64034
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-64034 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-64034 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 20, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 19, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f', 'lessThan': 'a201c66edf2ebc6cfdc3813a889ba20fecebfae3', 'versionType': 'git'}, {'status': 'affected', 'version': 'ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f', 'lessThan': '70ad2dff8d052a85dfef15715b531f38a29108cf', 'versionType': 'git'}, {'status': 'affected', 'version': 'ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f', 'lessThan': '566f42fb67a7ebfed6650e407e5b72e6b3e83bf7', 'versionType': 'git'}, {'status': 'affected', 'version': 'ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f', 'lessThan': '6180a06bbc99fd9114b8db4be6c4d46e40f046ef', 'versionType': 'git'}, {'status': 'affected', 'version': 'ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f', 'lessThan': '09ec063d87c2dd3fa6f3561361a017bd882e9f37', 'versionType': 'git'}, {'status': 'affected', 'version': 'ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f', 'lessThan': '3c4db56ccd13dd020fbf43afabaee74a40ec75e4', 'versionType': 'git'}, {'status': 'affected', 'version': 'ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f', 'lessThan': '35f0f0a2536a4d604b4dbad92c85c4a8fdebb870', 'versionType': 'git'}], 'programFiles': ['drivers/net/ethernet/microsoft/mana/hw_channel.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5.13'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.13', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.15.209', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.175', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.142', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.92', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.34', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.0.11', 'versionType': 'semver', 'lessThanOrEqual': '7.0.*'}, {'status': 'unaffected', 'version': '7.1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['drivers/net/ethernet/microsoft/mana/hw_channel.c'], 'defaultStatus': 'affected'}] Added Description 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 bounds validation. Fix this by reading hwc_msg_id exactly once using READ_ONCE() into a stack-local variable in mana_hwc_rx_event_handler(), and passing the validated value as a parameter to mana_hwc_handle_resp(). Added Reference https://git.kernel.org/stable/c/09ec063d87c2dd3fa6f3561361a017bd882e9f37 Added Reference https://git.kernel.org/stable/c/35f0f0a2536a4d604b4dbad92c85c4a8fdebb870 Added Reference https://git.kernel.org/stable/c/3c4db56ccd13dd020fbf43afabaee74a40ec75e4 Added Reference https://git.kernel.org/stable/c/566f42fb67a7ebfed6650e407e5b72e6b3e83bf7 Added Reference https://git.kernel.org/stable/c/6180a06bbc99fd9114b8db4be6c4d46e40f046ef Added Reference https://git.kernel.org/stable/c/70ad2dff8d052a85dfef15715b531f38a29108cf Added Reference https://git.kernel.org/stable/c/a201c66edf2ebc6cfdc3813a889ba20fecebfae3