CVE-2021-47568

Service interruption via leaked stream-name buffers

Published May 24, 2024 · Updated May 11, 2026

Memory leak in Linux kernel 5.15 ksmbd allows local users to exhaust kernel memory through crafted SMB file-stream queries. get_file_stream_info() allocates a stream-name buffer, then exits without freeing it when the encoded entry exceeds the response buffer. The ksmbd SMB server must be enabled, and repeated reachable queries can exhaust memory and interrupt the host.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in Linux kernel 5.15 ksmbd allows local users to exhaust kernel memory through crafted SMB file-stream queries. get_file_stream_info() allocates a stream-name buffer, then exits without freeing it when the encoded entry exceeds the response buffer. The ksmbd SMB server must be enabled, and repeated reachable queries can exhaust memory and interrupt the host.

The record

CVE
CVE-2021-47568
Published
May 24, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.003
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 24, 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=34061d6b76a41b1e43c19e1e50d98e5d77f77d4e <11e659827c3a2facb3a04e08cc97ff14d5091f51
  2. Affected versionversion=34061d6b76a41b1e43c19e1e50d98e5d77f77d4e <178ca6f85aa3231094467691f5ea1ff2f398aa8d
  3. Affected versionversion=5.15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=34061d6b76a41b1e43c19e1e50d98e5d77f77d4e <11e659827c3a2facb3a04e08cc97ff14d5091f51; version=34061d6b76a41b1e43c19e1e50d98e5d77f77d4e <178ca6f85aa3231094467691f5ea1ff2f398aa8d; version=5.15

Published CVSS scores

5.5NIST NVDCVSS: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 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

T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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