CVE-2023-53840

Out-of-bounds read via unterminated xHCI trace buffer

Published Dec 9, 2025 · Updated May 11, 2026

Out-of-bounds read in the xHCI DbC early console in Linux allows attackers to trigger an out-of-bounds kernel memory access. After xdbc_bulk_write() fails, early_xdbc_write() passes a full, non-NUL-terminated static buffer to xdbc_trace() as a %s string, causing formatting to read past the allocation. Reachability requires an x86 debugging kernel with CONFIG_EARLY_PRINTK_USB_XDBC enabled, the earlyprintk=xdbc boot parameter, xHCI DbC hardware, and a failed bulk write; the published record specifies no resulting disclosure or crash.

CVSS severityUnavailable
Unscored
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in the xHCI DbC early console in Linux allows attackers to trigger an out-of-bounds kernel memory access. After xdbc_bulk_write() fails, early_xdbc_write() passes a full, non-NUL-terminated static buffer to xdbc_trace() as a %s string, causing formatting to read past the allocation. Reachability requires an x86 debugging kernel with CONFIG_EARLY_PRINTK_USB_XDBC enabled, the earlyprintk=xdbc boot parameter, xHCI DbC hardware, and a failed bulk write; the published record specifies no resulting disclosure or crash.

The record

CVE
CVE-2023-53840
Published
Dec 9, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 9, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=4.12
  2. Affected versionversion=aeb9dd1de98c1a5f2007ea5d2a154c1244caf8a0 <351c8d8650d1ccc006255fa01f98b6c6496a02e5
  3. Affected versionversion=aeb9dd1de98c1a5f2007ea5d2a154c1244caf8a0 <a4a97ab3db5c081eb6e7dba91306adefb461e0bd
  4. Affected versionversion=aeb9dd1de98c1a5f2007ea5d2a154c1244caf8a0 <df7c8aba7309f4dc55df94e06b67f576c0f52406
  5. Affected versionversion=aeb9dd1de98c1a5f2007ea5d2a154c1244caf8a0 <e8fb0f13e45cf361fd06593d3cb2d89915cd3bd0

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=4.12; version=aeb9dd1de98c1a5f2007ea5d2a154c1244caf8a0 <351c8d8650d1ccc006255fa01f98b6c6496a02e5; version=aeb9dd1de98c1a5f2007ea5d2a154c1244caf8a0 <a4a97ab3db5c081eb6e7dba91306adefb461e0bd; version=aeb9dd1de98c1a5f2007ea5d2a154c1244caf8a0 <df7c8aba7309f4dc55df94e06b67f576c0f52406; version=aeb9dd1de98c1a5f2007ea5d2a154c1244caf8a0 <e8fb0f13e45cf361fd06593d3cb2d89915cd3bd0

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

Weakness, pattern, technique

No sourced classifications are available.

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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