CVE-2021-47131Network attack vector

Kernel memory corruption via stale TLS context

Published Mar 15, 2024 · Updated Aug 5, 2026

Use-after-free in Linux kernel kTLS device offload allows remote attackers to corrupt kernel memory through resumed TLS traffic. tls_device_down frees the offload context while a live socket retains its pointer, so RX resynchronization after the device returns dereferences released driver state. Reachability requires an established hardware-offloaded kTLS connection, a network-device down/up cycle, and subsequent TCP retransmissions; the result includes a kernel crash or control-flow compromise.

CVSS severity7.8
High
EPSS probability0.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux kernel kTLS device offload allows remote attackers to corrupt kernel memory through resumed TLS traffic. tls_device_down frees the offload context while a live socket retains its pointer, so RX resynchronization after the device returns dereferences released driver state. Reachability requires an established hardware-offloaded kTLS connection, a network-device down/up cycle, and subsequent TCP retransmissions; the result includes a kernel crash or control-flow compromise.

The record

CVE
CVE-2021-47131
Published
Mar 15, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1190
Attack vector
network
Privileges
unauthenticated

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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.18
  2. Affected versionversion=e8f69799810c32dd40c6724d829eccc70baad07f <0f1e6fe66977a864fe850522316f713d7b926fd9
  3. Affected versionversion=e8f69799810c32dd40c6724d829eccc70baad07f <c55dcdd435aa6c6ad6ccac0a4c636d010ee367a4
  4. Affected versionversion=e8f69799810c32dd40c6724d829eccc70baad07f <f1d4184f128dede82a59a841658ed40d4e6d3aa2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.18; version=e8f69799810c32dd40c6724d829eccc70baad07f <0f1e6fe66977a864fe850522316f713d7b926fd9; version=e8f69799810c32dd40c6724d829eccc70baad07f <c55dcdd435aa6c6ad6ccac0a4c636d010ee367a4; version=e8f69799810c32dd40c6724d829eccc70baad07f <f1d4184f128dede82a59a841658ed40d4e6d3aa2

Published CVSS scores

7.8UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1190Exploit Public-Facing Application

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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