CVE-2021-47250

Local denial of service via unreleased CIPSO mappings

Published May 21, 2024 · Updated May 11, 2026

Memory leak in affected Linux kernels allows local users to exhaust kernel memory through crafted NetLabel CIPSO requests. netlbl_cipsov4_add_std allocates doi_def->map.std, but cipso_v4_doi_free fails to release it when the DOI resource is freed. Low-privileged local access is required; repeated DOI operations consume unreclaimed kernel memory and can interrupt service.

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 affected Linux kernels allows local users to exhaust kernel memory through crafted NetLabel CIPSO requests. netlbl_cipsov4_add_std allocates doi_def->map.std, but cipso_v4_doi_free fails to release it when the DOI resource is freed. Low-privileged local access is required; repeated DOI operations consume unreclaimed kernel memory and can interrupt service.

The record

CVE
CVE-2021-47250
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.001
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=2.6.19
  2. Affected versionversion=96cb8e3313c7a12e026c1ed510522ae6f6023875 <086e92b1d68c6338535f715aad173f8cf4bfbc8c
  3. Affected versionversion=96cb8e3313c7a12e026c1ed510522ae6f6023875 <0ffb460be3abac86f884a8c548bb02724ec370f4
  4. Affected versionversion=96cb8e3313c7a12e026c1ed510522ae6f6023875 <212166510582631994be4f4b3fe15e10a03c1dd4
  5. Affected versionversion=96cb8e3313c7a12e026c1ed510522ae6f6023875 <398a24447eb60f060c8994221cb5ae6caf355fa1
  6. Affected versionversion=96cb8e3313c7a12e026c1ed510522ae6f6023875 <5340858147e3dc60913fb3dd0cbb758ec4a26e66
  7. Affected versionversion=96cb8e3313c7a12e026c1ed510522ae6f6023875 <6dcea66d3bb519b426282588f38e884e07893c1f
  8. Affected versionversion=96cb8e3313c7a12e026c1ed510522ae6f6023875 <d612c3f3fae221e7ea736d196581c2217304bbbc
  9. Affected versionversion=96cb8e3313c7a12e026c1ed510522ae6f6023875 <deeeb65c6ee404f2d1fb80b38b2730645c0f4663

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.19; version=96cb8e3313c7a12e026c1ed510522ae6f6023875 <086e92b1d68c6338535f715aad173f8cf4bfbc8c; version=96cb8e3313c7a12e026c1ed510522ae6f6023875 <0ffb460be3abac86f884a8c548bb02724ec370f4; version=96cb8e3313c7a12e026c1ed510522ae6f6023875 <212166510582631994be4f4b3fe15e10a03c1dd4; version=96cb8e3313c7a12e026c1ed510522ae6f6023875 <398a24447eb60f060c8994221cb5ae6caf355fa1; version=96cb8e3313c7a12e026c1ed510522ae6f6023875 <5340858147e3dc60913fb3dd0cbb758ec4a26e66; version=96cb8e3313c7a12e026c1ed510522ae6f6023875 <6dcea66d3bb519b426282588f38e884e07893c1f; version=96cb8e3313c7a12e026c1ed510522ae6f6023875 <d612c3f3fae221e7ea736d196581c2217304bbbc; version=96cb8e3313c7a12e026c1ed510522ae6f6023875 <deeeb65c6ee404f2d1fb80b38b2730645c0f4663

Published CVSS scores

5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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
T1499.001OS Exhaustion Flood

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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