CVE-2021-47305

Service interruption via sync-file fence leaks

Published May 21, 2024 · Updated May 11, 2026

Resource leak in the Linux kernel's dma-buf component allows local users to exhaust memory through repeated failed sync-file merges. The sync_file merge path calls dma_fence_get() for each fence but omits matching dma_fence_put() calls after add_fence() failures and can leave the fences array allocated after krealloc_array() failures. A low-privileged local process must repeatedly drive these failure paths; resulting kernel-memory depletion can interrupt service without exposing or modifying data.

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

Resource leak in the Linux kernel's dma-buf component allows local users to exhaust memory through repeated failed sync-file merges. The sync_file merge path calls dma_fence_get() for each fence but omits matching dma_fence_put() calls after add_fence() failures and can leave the fences array allocated after krealloc_array() failures. A low-privileged local process must repeatedly drive these failure paths; resulting kernel-memory depletion can interrupt service without exposing or modifying data.

The record

CVE
CVE-2021-47305
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-617, T1499.004
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=4.9
  2. Affected versionversion=a02b9dc90d844cc7df7b63264e7920cc425052d9 <0d514185ae792d3a1903c8e1a83899aa996705ce
  3. Affected versionversion=a02b9dc90d844cc7df7b63264e7920cc425052d9 <19edcd97727aae9362444a859a24d99a8730cb27
  4. Affected versionversion=a02b9dc90d844cc7df7b63264e7920cc425052d9 <19f51c2529339280d2c8c6427cd3e21ddf1ac3f8
  5. Affected versionversion=a02b9dc90d844cc7df7b63264e7920cc425052d9 <41f45e91c92c8480242ea448d54e28c753b13902
  6. Affected versionversion=a02b9dc90d844cc7df7b63264e7920cc425052d9 <e0355a0ad31a1d677b2a4514206de4902bd550e8
  7. Affected versionversion=a02b9dc90d844cc7df7b63264e7920cc425052d9 <ffe000217c5068c5da07ccb1c0f8cce7ad767435

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.9; version=a02b9dc90d844cc7df7b63264e7920cc425052d9 <0d514185ae792d3a1903c8e1a83899aa996705ce; version=a02b9dc90d844cc7df7b63264e7920cc425052d9 <19edcd97727aae9362444a859a24d99a8730cb27; version=a02b9dc90d844cc7df7b63264e7920cc425052d9 <19f51c2529339280d2c8c6427cd3e21ddf1ac3f8; version=a02b9dc90d844cc7df7b63264e7920cc425052d9 <41f45e91c92c8480242ea448d54e28c753b13902; version=a02b9dc90d844cc7df7b63264e7920cc425052d9 <e0355a0ad31a1d677b2a4514206de4902bd550e8; version=a02b9dc90d844cc7df7b63264e7920cc425052d9 <ffe000217c5068c5da07ccb1c0f8cce7ad767435

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-617Reachable Assertion
T1499.004Application or System Exploitation

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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