CVE-2023-53863

Kernel-memory disclosure via oversized FDB address attributes

Published Dec 9, 2025 · Updated May 11, 2026

Information disclosure in Linux before 6.5 allows local users to read uninitialized kernel memory through netlink FDB dumps. nlmsg_populate_fdb_fill uses the six-byte ETH_ALEN constant for NDA_LLADDR instead of the device's addr_len, appending two uninitialized bytes for a four-byte address. The path requires local low-privileged access and an affected network device, and the disclosed bytes can reveal kernel memory contents.

CVSS severity5.5
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Linux before 6.5 allows local users to read uninitialized kernel memory through netlink FDB dumps. nlmsg_populate_fdb_fill uses the six-byte ETH_ALEN constant for NDA_LLADDR instead of the device's addr_len, appending two uninitialized bytes for a four-byte address. The path requires local low-privileged access and an affected network device, and the disclosed bytes can reveal kernel memory contents.

The record

CVE
CVE-2023-53863
Published
Dec 9, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1005
Attack vector
local
Privileges
authenticated

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=3.5
  2. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <44db85c6e1a184b99a2cdf56b525ac63c4962c22
  3. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <619384319b137908d1008c92426c9daa95c06b90
  4. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <61d1bf3c34bf5fe936c50d1a4bc460babcc85e88
  5. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <73862118bd9dec850aa8e775145647ddd23aedf8
  6. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <aa5406950726e336c5c9585b09799a734b6e77bf
  7. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <b6f2d4618fc697886ad41e215ae20638153e42d0
  8. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <bd1de6107f10e7d4c2aabe3397b58d63672fc511
  9. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <c3ad49ff5c030cbe719fc4cb0ae081b8255ef4b3
  10. Affected versionversion=d83b060360485454fcd6870340ec01d6f96f2295 <e9331c8fa4c69f09d2c71682af75586f77266e81

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.5; version=d83b060360485454fcd6870340ec01d6f96f2295 <44db85c6e1a184b99a2cdf56b525ac63c4962c22; version=d83b060360485454fcd6870340ec01d6f96f2295 <619384319b137908d1008c92426c9daa95c06b90; version=d83b060360485454fcd6870340ec01d6f96f2295 <61d1bf3c34bf5fe936c50d1a4bc460babcc85e88; version=d83b060360485454fcd6870340ec01d6f96f2295 <73862118bd9dec850aa8e775145647ddd23aedf8; version=d83b060360485454fcd6870340ec01d6f96f2295 <aa5406950726e336c5c9585b09799a734b6e77bf; version=d83b060360485454fcd6870340ec01d6f96f2295 <b6f2d4618fc697886ad41e215ae20638153e42d0; version=d83b060360485454fcd6870340ec01d6f96f2295 <bd1de6107f10e7d4c2aabe3397b58d63672fc511; version=d83b060360485454fcd6870340ec01d6f96f2295 <c3ad49ff5c030cbe719fc4cb0ae081b8255ef4b3; version=d83b060360485454fcd6870340ec01d6f96f2295 <e9331c8fa4c69f09d2c71682af75586f77266e81

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1005Data from Local System

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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