CVE-2021-47014

Kernel crash via corrupted fragment control block

Published Feb 28, 2024 · Updated Aug 5, 2026

Memory corruption in Linux kernel act_ct in 5.7.12 through 5.12.3 allows local users to crash the kernel via crafted IP fragments. After fragment handling returns -EINPROGRESS, act_ct restores the skb qdisc control block and places unrelated data in FRAG_CB, which is later dereferenced during rbtree purge. Reachability requires local access and act_ct reassembly or refragmentation; the published evidence demonstrates a kernel crash but does not document code execution.

CVSS severity7.8
High
EPSS probability0.23%
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 act_ct in 5.7.12 through 5.12.3 allows local users to crash the kernel via crafted IP fragments. After fragment handling returns -EINPROGRESS, act_ct restores the skb qdisc control block and places unrelated data in FRAG_CB, which is later dereferenced during rbtree purge. Reachability requires local access and act_ct reassembly or refragmentation; the published evidence demonstrates a kernel crash but does not document code execution.

The record

CVE
CVE-2021-47014
Published
Feb 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-754, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 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=5.7.12 <5.8
  2. Affected versionversion=5.8
  3. Affected versionversion=ae372cb1750f6c95370f92fe5f5620e0954663ba <0648941f4c8bbf8b4b6c0b270889ae7aa769b921
  4. Affected versionversion=ae372cb1750f6c95370f92fe5f5620e0954663ba <f77bd544a6bbe69aa50d9ed09f13494cf36ff806
  5. Affected versionversion=fbff97eb6f4a94a3f15f685bed604c9adc29ac3e

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.7.12 <5.8; version=5.8; version=ae372cb1750f6c95370f92fe5f5620e0954663ba <0648941f4c8bbf8b4b6c0b270889ae7aa769b921; version=ae372cb1750f6c95370f92fe5f5620e0954663ba <f77bd544a6bbe69aa50d9ed09f13494cf36ff806; version=fbff97eb6f4a94a3f15f685bed604c9adc29ac3e

Published CVSS scores

7.8NIST NVDCVSS: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.

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1499Endpoint Denial of Service

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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