CVE-2021-47330

Local denial of service via serial probe leak

Published May 21, 2024 · Updated May 11, 2026

Memory leak in the Linux kernel serial_cs driver before 5.14 allows local users to exhaust memory when serial device setup fails. The serial_probe function allocates an info structure with kzalloc, but the failing serial_config path returned without freeing that allocation. Reachability requires low-privileged local access and a PCMCIA serial-device configuration that drives serial_config into its failure path; repeated triggers can degrade availability through kernel-memory exhaustion.

CVSS severity5.5
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in the Linux kernel serial_cs driver before 5.14 allows local users to exhaust memory when serial device setup fails. The serial_probe function allocates an info structure with kzalloc, but the failing serial_config path returned without freeing that allocation. Reachability requires low-privileged local access and a PCMCIA serial-device configuration that drives serial_config into its failure path; repeated triggers can degrade availability through kernel-memory exhaustion.

The record

CVE
CVE-2021-47330
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <331f5923fce4f45b8170ccf06c529e8eb28f37bc
  2. Affected versionversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <34f4590f5ec9859ea9136249f528173d150bd584
  3. Affected versionversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <7a80f71601af015856a0aeb1e3c294037ac3dd32
  4. Affected versionversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <b2ef1f5de40342de44fc5355321595f91774dab5
  5. Affected versionversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <b5a2799cd62ed30c81b22c23028d9ee374e2138c
  6. Affected versionversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <c39cf4df19acf0133fa284a8cd83fad42cd13cc2
  7. Affected versionversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <cddee5c287e26f6b2ba5c0ffdfc3a846f2f10461
  8. Affected versionversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <ee16bed959862a6de2913f71a04cb563d7237b67
  9. Affected versionversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <fad92b11047a748c996ebd6cfb164a63814eeb2e
  10. Affected versionversion=2.6.17

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <331f5923fce4f45b8170ccf06c529e8eb28f37bc; version=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <34f4590f5ec9859ea9136249f528173d150bd584; version=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <7a80f71601af015856a0aeb1e3c294037ac3dd32; version=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <b2ef1f5de40342de44fc5355321595f91774dab5; version=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <b5a2799cd62ed30c81b22c23028d9ee374e2138c; version=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <c39cf4df19acf0133fa284a8cd83fad42cd13cc2; version=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <cddee5c287e26f6b2ba5c0ffdfc3a846f2f10461; version=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <ee16bed959862a6de2913f71a04cb563d7237b67; version=15b99ac1729503db9e6dc642a50b9b6cb3bf51f9 <fad92b11047a748c996ebd6cfb164a63814eeb2e; version=2.6.17

Published CVSS scores

5.5NVDCVSS: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-401Missing Release of Memory after Effective Lifetime
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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