CVE-2021-47132

Memory corruption via unlocked MPTCP retransmission

Published Mar 15, 2024 · Updated Aug 5, 2026

Memory corruption in Linux kernel MPTCP 5.12 through 5.12.9 allows attackers to corrupt socket accounting during retransmission. The __mptcp_retrans path calls __mptcp_clean_una_wakeup without the MPTCP socket spin lock, while its helpers modify sk_forward_alloc. The public record identifies no attacker-controlled input or demonstrated consequence beyond corruption of that accounting field.

CVSS severityUnavailable
Unscored
EPSS probability0.48%
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 Linux kernel MPTCP 5.12 through 5.12.9 allows attackers to corrupt socket accounting during retransmission. The __mptcp_retrans path calls __mptcp_clean_una_wakeup without the MPTCP socket spin lock, while its helpers modify sk_forward_alloc. The public record identifies no attacker-controlled input or demonstrated consequence beyond corruption of that accounting field.

The record

CVE
CVE-2021-47132
Published
Mar 15, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Mar 15, 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=5.11.4 <5.12
  2. Affected versionversion=5.12
  3. Affected versionversion=64b9cea7a0afe579dd2682f1f1c04f2e4e72fd25 <b5941f066b4ca331db225a976dae1d6ca8cf0ae3
  4. Affected versionversion=64b9cea7a0afe579dd2682f1f1c04f2e4e72fd25 <b9c78b1a95966a7bd2ddae05b73eafc0cda4fba3
  5. Affected versionversion=96db8ffef07516a6d7414b6988f2a4298a839977

What conditions does exploitation require?

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

What is affected?

The Linux Kernel Organization · Linuxversion=5.11.4 <5.12; version=5.12; version=64b9cea7a0afe579dd2682f1f1c04f2e4e72fd25 <b5941f066b4ca331db225a976dae1d6ca8cf0ae3; version=64b9cea7a0afe579dd2682f1f1c04f2e4e72fd25 <b9c78b1a95966a7bd2ddae05b73eafc0cda4fba3; version=96db8ffef07516a6d7414b6988f2a4298a839977

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

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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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