CVE-2026-63956

Kernel memory corruption via undersized USB endpoint

Published Jul 19, 2026 · Updated Jul 19, 2026

Memory corruption in the Linux Kernel cypress_m8 USB serial driver allows physically proximate attackers to corrupt memory via a USB device. The driver fails to reject an interrupt-out endpoint whose reported maximum packet size is below eight bytes before using that endpoint for output, leading to slab corruption or a NULL-pointer dereference. Physical connection of a device presenting the undersized endpoint is required; the resulting corruption can crash the host kernel.

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

Memory corruption in the Linux Kernel cypress_m8 USB serial driver allows physically proximate attackers to corrupt memory via a USB device. The driver fails to reject an interrupt-out endpoint whose reported maximum packet size is below eight bytes before using that endpoint for output, leading to slab corruption or a NULL-pointer dereference. Physical connection of a device presenting the undersized endpoint is required; the resulting corruption can crash the host kernel.

The record

CVE
CVE-2026-63956
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1200
Attack vector
physical
Privileges
Unavailable

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=2.6.26
  2. Affected versionversion=3416eaa1f8f8d516b77de514e14cf8da256d28fb <1ef25704bd3b625fd151c09feee459479f71ee64
  3. Affected versionversion=3416eaa1f8f8d516b77de514e14cf8da256d28fb <284105c40fc31fff90cdab8a0377aaeb92f87f0e
  4. Affected versionversion=3416eaa1f8f8d516b77de514e14cf8da256d28fb <4bcaa59f403dbde6328604a500d65ee8d40975d9
  5. Affected versionversion=3416eaa1f8f8d516b77de514e14cf8da256d28fb <4fcb22218f0a7229b7ce3b3952fb644def293fa5
  6. Affected versionversion=3416eaa1f8f8d516b77de514e14cf8da256d28fb <52e18ae0c47c5c89e18fcd8022f287f7cc8802ec
  7. Affected versionversion=3416eaa1f8f8d516b77de514e14cf8da256d28fb <6c13f3bb652bc8665e709ba07122612586aea648
  8. Affected versionversion=3416eaa1f8f8d516b77de514e14cf8da256d28fb <ad3d1628a46134276546d7a12fedf04be9979158
  9. Affected versionversion=3416eaa1f8f8d516b77de514e14cf8da256d28fb <e1a9d791fd66ab2431b9e6f6f835823809869047

What conditions does exploitation require?

Attack vectorphysical
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.26; version=3416eaa1f8f8d516b77de514e14cf8da256d28fb <1ef25704bd3b625fd151c09feee459479f71ee64; version=3416eaa1f8f8d516b77de514e14cf8da256d28fb <284105c40fc31fff90cdab8a0377aaeb92f87f0e; version=3416eaa1f8f8d516b77de514e14cf8da256d28fb <4bcaa59f403dbde6328604a500d65ee8d40975d9; version=3416eaa1f8f8d516b77de514e14cf8da256d28fb <4fcb22218f0a7229b7ce3b3952fb644def293fa5; version=3416eaa1f8f8d516b77de514e14cf8da256d28fb <52e18ae0c47c5c89e18fcd8022f287f7cc8802ec; version=3416eaa1f8f8d516b77de514e14cf8da256d28fb <6c13f3bb652bc8665e709ba07122612586aea648; version=3416eaa1f8f8d516b77de514e14cf8da256d28fb <ad3d1628a46134276546d7a12fedf04be9979158; version=3416eaa1f8f8d516b77de514e14cf8da256d28fb <e1a9d791fd66ab2431b9e6f6f835823809869047

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

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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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
PrivilegesUnavailable
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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