CVE-2021-47649

Kernel crash via zero-page-count udmabuf allocation

Published Feb 26, 2025 · Updated May 11, 2026

Improper input validation in Linux kernel udmabuf allows local users to crash the kernel through a zero-size creation request. The udmabuf creation path derives ubuf->pagecount from the user-supplied list size and passes zero to kmalloc_array, leaving ubuf->pages as ZERO_PTR before scatter-gather allocation. A local user able to submit an udmabuf creation request can trigger a general protection fault and interrupt the host.

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

Improper input validation in Linux kernel udmabuf allows local users to crash the kernel through a zero-size creation request. The udmabuf creation path derives ubuf->pagecount from the user-supplied list size and passes zero to kmalloc_array, leaving ubuf->pages as ZERO_PTR before scatter-gather allocation. A local user able to submit an udmabuf creation request can trigger a general protection fault and interrupt the host.

The record

CVE
CVE-2021-47649
Published
Feb 26, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 26, 2025CVE 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=4.20
  2. Affected versionversion=fbb0de795078190a9834b3409e4b009cfb18a6d4 <2b6dd600dd72573c23ea180b5b0b2f1813405882
  3. Affected versionversion=fbb0de795078190a9834b3409e4b009cfb18a6d4 <5d50f851dd307c07ca5591297093f19967c834a9
  4. Affected versionversion=fbb0de795078190a9834b3409e4b009cfb18a6d4 <811b667cefbea9cb7511a874b169d6a92907137e
  5. Affected versionversion=fbb0de795078190a9834b3409e4b009cfb18a6d4 <9e9b4a269f84d3230f2af84ff42322db676440d9
  6. Affected versionversion=fbb0de795078190a9834b3409e4b009cfb18a6d4 <a3728d32fc61eb0fe283cb8ff60b2c8f751e2202
  7. Affected versionversion=fbb0de795078190a9834b3409e4b009cfb18a6d4 <b267a8118c2b171bf7d67b90ed64154eeab9fae0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.20; version=fbb0de795078190a9834b3409e4b009cfb18a6d4 <2b6dd600dd72573c23ea180b5b0b2f1813405882; version=fbb0de795078190a9834b3409e4b009cfb18a6d4 <5d50f851dd307c07ca5591297093f19967c834a9; version=fbb0de795078190a9834b3409e4b009cfb18a6d4 <811b667cefbea9cb7511a874b169d6a92907137e; version=fbb0de795078190a9834b3409e4b009cfb18a6d4 <9e9b4a269f84d3230f2af84ff42322db676440d9; version=fbb0de795078190a9834b3409e4b009cfb18a6d4 <a3728d32fc61eb0fe283cb8ff60b2c8f751e2202; version=fbb0de795078190a9834b3409e4b009cfb18a6d4 <b267a8118c2b171bf7d67b90ed64154eeab9fae0

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

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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