CVE-2021-47240

Host crash via wrapped QRTR size validation

Published May 21, 2024 · Updated Aug 5, 2026

Out-of-bounds read in Linux kernel 4.15 and later affected branches allows attackers to crash a host with a crafted QRTR packet. In qrtr_endpoint_post, a size near UINT_MAX wraps ALIGN(size, 4) to zero, bypassing the length check before skb_put_data copies the declared size from a header-sized buffer. Reachability requires a local QRTR endpoint, such as an MHI or SMD peripheral path or /dev/qrtr-tun; the kernel over-read can expose memory or crash the host.

CVSS severity8.4
High
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

Out-of-bounds read in Linux kernel 4.15 and later affected branches allows attackers to crash a host with a crafted QRTR packet. In qrtr_endpoint_post, a size near UINT_MAX wraps ALIGN(size, 4) to zero, bypassing the length check before skb_put_data copies the declared size from a header-sized buffer. Reachability requires a local QRTR endpoint, such as an MHI or SMD peripheral path or /dev/qrtr-tun; the kernel over-read can expose memory or crash the host.

The record

CVE
CVE-2021-47240
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-125, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=194ccc88297ae78d0803adad83c6dcc369787c9e <19892ab9c9d838e2e5a7744d36e4bb8b7c3292fe
  2. Affected versionversion=194ccc88297ae78d0803adad83c6dcc369787c9e <26b8d10703a9be45d6097946b2b4011f7dd2c56f
  3. Affected versionversion=194ccc88297ae78d0803adad83c6dcc369787c9e <960b08dd36de1e341e3eb43d1c547513e338f4f8
  4. Affected versionversion=194ccc88297ae78d0803adad83c6dcc369787c9e <ad9d24c9429e2159d1e279dc3a83191ccb4daf1d
  5. Affected versionversion=194ccc88297ae78d0803adad83c6dcc369787c9e <f8111c0d7ed42ede41a3d0d393b104de0730a8a6
  6. Affected versionversion=4.15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=194ccc88297ae78d0803adad83c6dcc369787c9e <19892ab9c9d838e2e5a7744d36e4bb8b7c3292fe; version=194ccc88297ae78d0803adad83c6dcc369787c9e <26b8d10703a9be45d6097946b2b4011f7dd2c56f; version=194ccc88297ae78d0803adad83c6dcc369787c9e <960b08dd36de1e341e3eb43d1c547513e338f4f8; version=194ccc88297ae78d0803adad83c6dcc369787c9e <ad9d24c9429e2159d1e279dc3a83191ccb4daf1d; version=194ccc88297ae78d0803adad83c6dcc369787c9e <f8111c0d7ed42ede41a3d0d393b104de0730a8a6; version=4.15

Published CVSS scores

6.1Red HatCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
7.1UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
8.4LinuxCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
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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