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NVD / CVE Program· CNA Linux

CVE-2026-64034: net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

Noroxi assessment

Priority: Monitor (action score 37/100)

  • 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: 0.11% (FIRST EPSS).
  • Someone with local access to the system can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 09ec063d87c2dd3fa6f3561361a017bd882e9f37, 35f0f0a2536a4d604b4dbad92c85c4a8fdebb870, 3c4db56ccd13dd020fbf43afabaee74a40ec75e4.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 09ec063d87c2dd3fa6f3561361a017bd882e9f37, 35f0f0a2536a4d604b4dbad92c85c4a8fdebb870, 3c4db56ccd13dd020fbf43afabaee74a40ec75e4 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: 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().

CriticalCVSS 9.3 · v3.1—No exploit Fix available
Published
Jul 19, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 1th percentile

Report tools

JSON

Action score

37

Monitor

Low priority for now.

CVSS
37 / 40 · 9.3 / 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
9.3
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.

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  • 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 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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.13 and later · before 5.15.209
  • linux linux kernel5.16 and later · before 6.1.175
  • linux linux kernel6.2 and later · before 6.6.142
  • linux linux kernel6.7 and later · before 6.12.92
  • linux linux kernel6.13 and later · before 6.18.34
  • linux linux kernel6.19 and later · before 7.0.11
  • linux linux kernel7.1

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

    • 5.13affected
    • ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and later · before a201c66edf2ebc6cfdc3813a889ba20fecebfae3affected · git
    • ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and later · before 70ad2dff8d052a85dfef15715b531f38a29108cfaffected · git
    • ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and later · before 566f42fb67a7ebfed6650e407e5b72e6b3e83bf7affected · git
    • ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and later · before 6180a06bbc99fd9114b8db4be6c4d46e40f046efaffected · git
    • ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and later · before 09ec063d87c2dd3fa6f3561361a017bd882e9f37affected · git
    • ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and later · before 3c4db56ccd13dd020fbf43afabaee74a40ec75e4affected · git
    • ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and later · before 35f0f0a2536a4d604b4dbad92c85c4a8fdebb870affected · git
    • before 5.13not affected · semver
    • 5.15.209 and later · up to and including 5.15.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.62.1.el10_26.12.0-211.62.1.el10_2

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-64032Jul 19, 2026 · bridge: mcast: Fix a possible use-after-free when removing a bridge port
    31Monitor
  • ← EarlierCVE-2026-64033Jul 19, 2026 · RDMA/rtrs: Fix use-after-free in path file creation cleanup
    39Monitor
  • Later →CVE-2026-64035Jul 19, 2026 · igc: set tx buffer type for SMD frames
    39Monitor

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 Linux09ec063d87c2dd3fa6f3561361a017bd882e9f37Vendor (CNA)
Linux Linux35f0f0a2536a4d604b4dbad92c85c4a8fdebb870Vendor (CNA)
Linux Linux3c4db56ccd13dd020fbf43afabaee74a40ec75e4Vendor (CNA)
Linux Linux566f42fb67a7ebfed6650e407e5b72e6b3e83bf7Vendor (CNA)
Linux Linux6180a06bbc99fd9114b8db4be6c4d46e40f046efVendor (CNA)
Linux Linux70ad2dff8d052a85dfef15715b531f38a29108cfVendor (CNA)
Linux Linuxa201c66edf2ebc6cfdc3813a889ba20fecebfae3Vendor (CNA)
almalinux:kernel5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-687.46.1.el9_8 · AlmaLinux:9Package registry (OSV)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel-matched0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debuginfo0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel-matched0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-debuginfo0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel-matched0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debuginfo0:5.14.0-687.46.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)

+4

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-2025-38352362 days apartposix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()KEV
    61This week
  • CVE-2026-640910 days apartbatman-adv: tt: fix TOCTOU race for reported vlans
    39Monitor
  • CVE-2026-639370 days apartKVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer
    35Monitor
  • CVE-2026-638670 days apartmptcp: close TOCTOU race while computing rcv_wnd
    32Monitor
  • CVE-2026-641120 days apartrbd: eliminate a race in lock_dwork draining on unmap
    31Monitor
  • CVE-2026-5314524 days apartdrm/gem: Try to fix change_handle ioctl, attempt 4
    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.
  • No account or password is required.
  • 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
None
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-367 · Time-of-check Time-of-use (TOCTOU) Race Condition

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/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

—

Change log

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

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

References

Show all references (6 more)

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

All records