CVE-2021-47523

Service interruption via hfi1 reinitialization memory leak

Published May 24, 2024 · Updated May 11, 2026

Memory leakage in the hfi1 driver in Linux kernel 4.5 through 5.16-rc4 allows local users to interrupt service through reinitialization. hfi1_init allocates new coherent DMA memory for rcvhdrtail_dummy_kvaddr during reinitialization, then overwrites the previous pointer without releasing its allocation. Reachability requires local low-privileged access and an hfi1 reinitialization; repeated leaks can exhaust memory and 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 leakage in the hfi1 driver in Linux kernel 4.5 through 5.16-rc4 allows local users to interrupt service through reinitialization. hfi1_init allocates new coherent DMA memory for rcvhdrtail_dummy_kvaddr during reinitialization, then overwrites the previous pointer without releasing its allocation. Reachability requires local low-privileged access and an hfi1 reinitialization; repeated leaks can exhaust memory and interrupt service.

The record

CVE
CVE-2021-47523
Published
May 24, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
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=4.5
  2. Affected versionversion=46b010d3eeb8eb29c740c4ef09c666485f5c07e6 <2c08271f4ed0e24633b3f81ceff61052b9d45efc
  3. Affected versionversion=46b010d3eeb8eb29c740c4ef09c666485f5c07e6 <60a8b5a1611b4a26de4839ab9c1fc2a9cf3e17c1
  4. Affected versionversion=46b010d3eeb8eb29c740c4ef09c666485f5c07e6 <834d0fb978643eaf09da425de197cc16a7c2761b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.5; version=46b010d3eeb8eb29c740c4ef09c666485f5c07e6 <2c08271f4ed0e24633b3f81ceff61052b9d45efc; version=46b010d3eeb8eb29c740c4ef09c666485f5c07e6 <60a8b5a1611b4a26de4839ab9c1fc2a9cf3e17c1; version=46b010d3eeb8eb29c740c4ef09c666485f5c07e6 <834d0fb978643eaf09da425de197cc16a7c2761b

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-401Missing Release of Memory after Effective Lifetime
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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