CVE-2021-47597

Kernel memory disclosure via uninitialized UDP diagnostics

Published Jun 19, 2024 · Updated May 11, 2026

Information disclosure in affected Linux kernels before 5.16 allows local users to read uninitialized kernel memory via UDP diagnostics. inet_sk_diag_fill() leaves the inet_diag_msg idiag_expires field uninitialized for UDP sockets, then netlink copies the structure to user space. A local unprivileged account can trigger the diagnostic response and obtain four bytes of residual kernel data; no write or service interruption is reported.

CVSS severity5.5
Medium
EPSS probability0.25%
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 affected Linux kernels before 5.16 allows local users to read uninitialized kernel memory via UDP diagnostics. inet_sk_diag_fill() leaves the inet_diag_msg idiag_expires field uninitialized for UDP sockets, then netlink copies the structure to user space. A local unprivileged account can trigger the diagnostic response and obtain four bytes of residual kernel data; no write or service interruption is reported.

The record

CVE
CVE-2021-47597
Published
Jun 19, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-908, T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 19, 2024CVE 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=3.3
  2. Affected versionversion=3c4d05c8056724aff3abc20650807dd828fded54 <3a4f6dba1eb98101abc012ef968a8b10dac1ce50
  3. Affected versionversion=3c4d05c8056724aff3abc20650807dd828fded54 <71ddeac8cd1d217744a0e060ff520e147c9328d1
  4. Affected versionversion=3c4d05c8056724aff3abc20650807dd828fded54 <7b5596e531253ce84213d9daa7120b71c9d83198
  5. Affected versionversion=3c4d05c8056724aff3abc20650807dd828fded54 <e5d28205bf1de7082d904ed277ceb2db2879e302

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.3; version=3c4d05c8056724aff3abc20650807dd828fded54 <3a4f6dba1eb98101abc012ef968a8b10dac1ce50; version=3c4d05c8056724aff3abc20650807dd828fded54 <71ddeac8cd1d217744a0e060ff520e147c9328d1; version=3c4d05c8056724aff3abc20650807dd828fded54 <7b5596e531253ce84213d9daa7120b71c9d83198; version=3c4d05c8056724aff3abc20650807dd828fded54 <e5d28205bf1de7082d904ed277ceb2db2879e302

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
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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