CVE-2021-47152

Service interruption via MPTCP page-fragment reuse

Published Mar 25, 2024 · Updated Aug 5, 2026

Memory corruption in MPTCP in the Linux kernel allows local users to interrupt service through a TCP transparent proxy. The mptcp_frag_can_collapse_to() helper assumes its page_frag is used only by MPTCP, so it can expand an MPTCP data fragment over memory already allocated by plain TCP. Exploitation requires mixed MPTCP and TCP page-fragment allocation in a transparent-proxy path; the resulting reuse corrupts the data stream and affects availability.

CVSS severity5.5
Medium
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

Memory corruption in MPTCP in the Linux kernel allows local users to interrupt service through a TCP transparent proxy. The mptcp_frag_can_collapse_to() helper assumes its page_frag is used only by MPTCP, so it can expand an MPTCP data fragment over memory already allocated by plain TCP. Exploitation requires mixed MPTCP and TCP page-fragment allocation in a transparent-proxy path; the resulting reuse corrupts the data stream and affects availability.

The record

CVE
CVE-2021-47152
Published
Mar 25, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 25, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=18b683bff89d46ace55f12d00c0440d44d6160c4 <18e7f0580da15cac1e79d73683ada5a9e70980f8
  2. Affected versionversion=18b683bff89d46ace55f12d00c0440d44d6160c4 <29249eac5225429b898f278230a6ca2baa1ae154
  3. Affected versionversion=18b683bff89d46ace55f12d00c0440d44d6160c4 <3267a061096efc91eda52c2a0c61ba76e46e4b34
  4. Affected versionversion=5.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=18b683bff89d46ace55f12d00c0440d44d6160c4 <18e7f0580da15cac1e79d73683ada5a9e70980f8; version=18b683bff89d46ace55f12d00c0440d44d6160c4 <29249eac5225429b898f278230a6ca2baa1ae154; version=18b683bff89d46ace55f12d00c0440d44d6160c4 <3267a061096efc91eda52c2a0c61ba76e46e4b34; version=5.7

Published CVSS scores

5.5UbuntuCVSS: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

T1499Endpoint Denial of Service

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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