CVE-2026-63899

Kernel memory corruption via undersized bulk-out endpoint

Published Jul 19, 2026 · Updated Jul 19, 2026

Memory corruption in the Linux Kernel mxuport USB serial driver allows physically proximate attackers to execute code via a malicious USB device. The driver accepts a bulk-out endpoint maximum packet size below eight bytes, allowing device-controlled slab corruption during buffer handling. Physical attachment and binding to the mxuport driver are required; the corruption can crash the kernel or enable arbitrary code execution.

CVSS severity7.0
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in the Linux Kernel mxuport USB serial driver allows physically proximate attackers to execute code via a malicious USB device. The driver accepts a bulk-out endpoint maximum packet size below eight bytes, allowing device-controlled slab corruption during buffer handling. Physical attachment and binding to the mxuport driver are required; the corruption can crash the kernel or enable arbitrary code execution.

The record

CVE
CVE-2026-63899
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-120, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.14
  2. Affected versionversion=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <086b858b5f5125bc9d967ea2bd825f83d9f8f29d
  3. Affected versionversion=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <2f3661eb2446e1ef593da45e01a3b21a906768ec
  4. Affected versionversion=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <4085f0dbb1ce2251c9a5938d693de6593f0ab2bd
  5. Affected versionversion=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <6c0cf56f00f280d72180bb6ce79741bc787a6269
  6. Affected versionversion=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <b40166b4ef96067620a0f248e74ad9658c8f680c
  7. Affected versionversion=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <be3a1ed4ae51fa8dde57383277d336ce834f2cd9
  8. Affected versionversion=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <ccbec56f2f9af008f1574335cc6a668f16603e47
  9. Affected versionversion=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <e906545641d34fb1a09a65b4b5cfdff40eb09681

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3.14; version=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <086b858b5f5125bc9d967ea2bd825f83d9f8f29d; version=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <2f3661eb2446e1ef593da45e01a3b21a906768ec; version=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <4085f0dbb1ce2251c9a5938d693de6593f0ab2bd; version=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <6c0cf56f00f280d72180bb6ce79741bc787a6269; version=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <b40166b4ef96067620a0f248e74ad9658c8f680c; version=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <be3a1ed4ae51fa8dde57383277d336ce834f2cd9; version=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <ccbec56f2f9af008f1574335cc6a668f16603e47; version=ee467a1f2066d2bfa293f7c2c7f1ff7000b0a39e <e906545641d34fb1a09a65b4b5cfdff40eb09681

Published CVSS scores

7.0Red HatCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
7.0SUSECVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
6.8SUSECVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
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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