CVE-2026-63962

Kernel memory corruption via unsolicited mode ACK

Published Jul 19, 2026 · Updated Jul 19, 2026

Out-of-bounds write in the Linux Kernel TCPM subsystem allows physically proximate attackers to corrupt kernel memory via USB-C messages. In svdm_consume_modes(), a single pre-loop altmode_desc[] bounds check permits an unsolicited Discover Modes ACK containing seven VDOs to drive up to five writes beyond the array. Reachability requires an established USB-C port partner; partner-controlled SVID/VDO bytes can overwrite the adjacent partner_altmode[] pointer array.

CVSS severityUnavailable
Unscored
EPSS probability0.21%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in the Linux Kernel TCPM subsystem allows physically proximate attackers to corrupt kernel memory via USB-C messages. In svdm_consume_modes(), a single pre-loop altmode_desc[] bounds check permits an unsolicited Discover Modes ACK containing seven VDOs to drive up to five writes beyond the array. Reachability requires an established USB-C port partner; partner-controlled SVID/VDO bytes can overwrite the adjacent partner_altmode[] pointer array.

The record

CVE
CVE-2026-63962
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1200
Attack vector
physical
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=0 <6.12.93
  2. Affected versionversion=0 <6.18.35
  3. Affected versionversion=0 <7.0.12
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3389c149c68c3fea61910ad5d34f7bf3bff44e32
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4505f33dab56c274e82f47f94bf60a8cbf8f4b42
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <845598b154b9a92e9d279fafafa9405c121ae805
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <cbad85b446c06adbc5e5bed565871bb918ce9d32

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0 <6.12.93; version=0 <6.18.35; version=0 <7.0.12; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3389c149c68c3fea61910ad5d34f7bf3bff44e32; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4505f33dab56c274e82f47f94bf60a8cbf8f4b42; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <845598b154b9a92e9d279fafafa9405c121ae805; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <cbad85b446c06adbc5e5bed565871bb918ce9d32

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1200Hardware Additions

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

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Your stack

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