CVE-2021-47397Network attack vector

Remote kernel crash via unchecked SCTP header pointer

Published May 21, 2024 · Updated Aug 5, 2026

NULL pointer dereference in Linux kernel SCTP handling allows remote attackers to crash the kernel with crafted IPv4 or IPv6 packets. In sctp_rcv_ootb in net/sctp/input.c, code dereferences the returned chunk-header pointer after skb_header_pointer returns NULL instead of stopping packet processing. Exposure requires the SCTP stack to be loaded; no local socket, authentication, or user interaction is required, and the consequence is a repeatable kernel crash.

CVSS severityUnavailable
Unscored
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux kernel SCTP handling allows remote attackers to crash the kernel with crafted IPv4 or IPv6 packets. In sctp_rcv_ootb in net/sctp/input.c, code dereferences the returned chunk-header pointer after skb_header_pointer returns NULL instead of stopping packet processing. Exposure requires the SCTP stack to be loaded; no local socket, authentication, or user interaction is required, and the consequence is a repeatable kernel crash.

The record

CVE
CVE-2021-47397
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 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=3acb50c18d8d6650f10919464ade4dcdaf41d62f <77bc7dcf0fcc1519341a91788d7a2914fcfddf6d
  2. Affected versionversion=3acb50c18d8d6650f10919464ade4dcdaf41d62f <8180611c238e11676612eb2a9828b1c7a3a4d77b
  3. Affected versionversion=3acb50c18d8d6650f10919464ade4dcdaf41d62f <8c630a7b4f9dec63f08bd881ab77984a724a5124
  4. Affected versionversion=3acb50c18d8d6650f10919464ade4dcdaf41d62f <9c6591ae8e63f93c895ad5e2703c36c548aac997
  5. Affected versionversion=3acb50c18d8d6650f10919464ade4dcdaf41d62f <ec018021cf445abbe8e2f3e2a7f1dcc813cb8ea1
  6. Affected versionversion=3acb50c18d8d6650f10919464ade4dcdaf41d62f <f7e745f8e94492a8ac0b0a26e25f2b19d342918f
  7. Affected versionversion=4.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3acb50c18d8d6650f10919464ade4dcdaf41d62f <77bc7dcf0fcc1519341a91788d7a2914fcfddf6d; version=3acb50c18d8d6650f10919464ade4dcdaf41d62f <8180611c238e11676612eb2a9828b1c7a3a4d77b; version=3acb50c18d8d6650f10919464ade4dcdaf41d62f <8c630a7b4f9dec63f08bd881ab77984a724a5124; version=3acb50c18d8d6650f10919464ade4dcdaf41d62f <9c6591ae8e63f93c895ad5e2703c36c548aac997; version=3acb50c18d8d6650f10919464ade4dcdaf41d62f <ec018021cf445abbe8e2f3e2a7f1dcc813cb8ea1; version=3acb50c18d8d6650f10919464ade4dcdaf41d62f <f7e745f8e94492a8ac0b0a26e25f2b19d342918f; version=4.8

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.

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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

T1499.004Application or System Exploitation

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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