CVE-2021-47564

Kernel crash via bridge-port error-path double free

Published May 24, 2024 · Updated May 11, 2026

A double free in the Prestera driver in Linux allows local users to crash the kernel when a bridge-port join operation fails. In prestera_bridge_port_join(), error cleanup dropped the bridge-port reference and then separately dropped the same bridge reference, although prestera_bridge_port_put() already releases that bridge when destroying the port. Reachability requires local bridge-management access on a system using the Prestera driver; the demonstrated consequence is a kernel crash.

CVSS severity7.8
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A double free in the Prestera driver in Linux allows local users to crash the kernel when a bridge-port join operation fails. In prestera_bridge_port_join(), error cleanup dropped the bridge-port reference and then separately dropped the same bridge reference, although prestera_bridge_port_put() already releases that bridge when destroying the port. Reachability requires local bridge-management access on a system using the Prestera driver; the demonstrated consequence is a kernel crash.

The record

CVE
CVE-2021-47564
Published
May 24, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-415, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 24, 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=5.10
  2. Affected versionversion=e1189d9a5fbec8153dbe03f3589bc2baa96694e2 <03e5203d2161a00afe4d97d206d2293e40b2f253
  3. Affected versionversion=e1189d9a5fbec8153dbe03f3589bc2baa96694e2 <5dca8eff4627315df98feec09fff9dfe3356325e
  4. Affected versionversion=e1189d9a5fbec8153dbe03f3589bc2baa96694e2 <e8d032507cb7912baf1d3e0af54516f823befefd

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.10; version=e1189d9a5fbec8153dbe03f3589bc2baa96694e2 <03e5203d2161a00afe4d97d206d2293e40b2f253; version=e1189d9a5fbec8153dbe03f3589bc2baa96694e2 <5dca8eff4627315df98feec09fff9dfe3356325e; version=e1189d9a5fbec8153dbe03f3589bc2baa96694e2 <e8d032507cb7912baf1d3e0af54516f823befefd

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.

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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-415Double Free
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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