CVE-2021-47606

Local kernel crash via empty Netlink packet

Published Jun 19, 2024 · Updated May 11, 2026

Divide by zero in the Linux kernel allows local users to crash the system by sending an empty packet through a Netlink socket. The af_netlink.c send path accepts a zero length, creates an empty socket buffer, and passes it to netem_enqueue, where randomized corruption takes a modulus by skb_headlen(skb). A local low-privileged process must reach the affected Netlink and netem path; the documented result is a kernel divide error and system availability loss.

CVSS severity5.5
Medium
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

Divide by zero in the Linux kernel allows local users to crash the system by sending an empty packet through a Netlink socket. The af_netlink.c send path accepts a zero length, creates an empty socket buffer, and passes it to netem_enqueue, where randomized corruption takes a modulus by skb_headlen(skb). A local low-privileged process must reach the affected Netlink and netem path; the documented result is a kernel divide error and system availability loss.

The record

CVE
CVE-2021-47606
Published
Jun 19, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-369, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 19, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=3.11
  2. Affected versionversion=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <40cf2e058832d9cfaae98dfd77334926275598b6
  3. Affected versionversion=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <4c986072a8c9249b9398c7a18f216dc26a9f0e35
  4. Affected versionversion=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <54e785f7d5c197bc06dbb8053700df7e2a093ced
  5. Affected versionversion=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <c0315e93552e0d840e9edc6abd71c7db82ec8f51
  6. Affected versionversion=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <c54a60c8fbaa774f828e26df79f66229a8a0e010
  7. Affected versionversion=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <dadce61247c6230489527cc5e343b6002d1114c5
  8. Affected versionversion=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <f123cffdd8fe8ea6c7fded4b88516a42798797d0
  9. Affected versionversion=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <ff3f517bf7138e01a17369042908a3f345c0ee41

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.11; version=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <40cf2e058832d9cfaae98dfd77334926275598b6; version=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <4c986072a8c9249b9398c7a18f216dc26a9f0e35; version=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <54e785f7d5c197bc06dbb8053700df7e2a093ced; version=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <c0315e93552e0d840e9edc6abd71c7db82ec8f51; version=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <c54a60c8fbaa774f828e26df79f66229a8a0e010; version=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <dadce61247c6230489527cc5e343b6002d1114c5; version=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <f123cffdd8fe8ea6c7fded4b88516a42798797d0; version=bcbde0d449eda7afa8f63280b165c8300dbd00e2 <ff3f517bf7138e01a17369042908a3f345c0ee41

Published CVSS scores

5.5NIST NVDCVSS: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

CWE-369Divide By Zero
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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