CVE-2021-20265

System crash via unreleased socket credentials

Published Mar 10, 2021 · Updated Aug 3, 2024

Resource exhaustion in Linux Kernel before 4.5-rc3 allows local users to crash the system through interrupted UNIX socket receives. When a signal is pending, unix_stream_read_generic exits its receive loop without calling scm_destroy, leaking a struct pid reference for each interruption. Any unprivileged local account that can repeatedly interrupt UNIX-domain socket receives can consume available memory until the host crashes.

CVSS severity5.5
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Linux Kernel before 4.5-rc3 allows local users to crash the system through interrupted UNIX socket receives. When a signal is pending, unix_stream_read_generic exits its receive loop without calling scm_destroy, leaking a struct pid reference for each interruption. Any unprivileged local account that can repeatedly interrupt UNIX-domain socket receives can consume available memory until the host crashes.

The record

CVE
CVE-2021-20265
Published
Mar 10, 2021
Updated
Aug 3, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-400, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=Linux kernel 4.5-rc3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=Linux kernel 4.5-rc3

Published CVSS scores

5.5OracleCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5OSVCVSS: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-400Uncontrolled Resource Consumption
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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