CVE-2021-47520

Kernel memory corruption via post-delivery frame access

Published May 24, 2024 · Updated Aug 5, 2026

Use-after-free in Linux 2.6.37 through 5.15.7 allows physically proximate attackers to corrupt kernel memory via CAN frames. In pch_can_rx_normal, netif_receive_skb consumes the socket buffer before the driver reads cf->len from the can_frame that aliases that buffer. The EG20T PCH CAN interface must be operational on the attacker's bus segment; exploitation can disclose memory, alter kernel execution, or panic the system.

CVSS severity7.8
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux 2.6.37 through 5.15.7 allows physically proximate attackers to corrupt kernel memory via CAN frames. In pch_can_rx_normal, netif_receive_skb consumes the socket buffer before the driver reads cf->len from the can_frame that aliases that buffer. The EG20T PCH CAN interface must be operational on the attacker's bus segment; exploitation can disclose memory, alter kernel execution, or panic the system.

The record

CVE
CVE-2021-47520
Published
May 24, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 24, 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=2.6.37
  2. Affected versionversion=b21d18b51b31a24d17f883b678432fbdee3d5675 <3a3c46e2eff0577454860a203be1a8295f4acb76
  3. Affected versionversion=b21d18b51b31a24d17f883b678432fbdee3d5675 <3e193ef4e0a3f5bf92ede83ef214cb09d01b00aa
  4. Affected versionversion=b21d18b51b31a24d17f883b678432fbdee3d5675 <6c73fc931658d8cbc8a1714b326cb31eb71d16a7
  5. Affected versionversion=b21d18b51b31a24d17f883b678432fbdee3d5675 <703dde112021c93d6e89443c070e7dbd4dea612e
  6. Affected versionversion=b21d18b51b31a24d17f883b678432fbdee3d5675 <94cddf1e9227a171b27292509d59691819c458db
  7. Affected versionversion=b21d18b51b31a24d17f883b678432fbdee3d5675 <abb4eff3dcd2e583060082a18a8dbf31f02689d4
  8. Affected versionversion=b21d18b51b31a24d17f883b678432fbdee3d5675 <affbad02bf80380a7403885b9fe4a1587d1bb4f3
  9. Affected versionversion=b21d18b51b31a24d17f883b678432fbdee3d5675 <bafe343a885c70dddf358379cf0b2a1c07355d8d

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.37; version=b21d18b51b31a24d17f883b678432fbdee3d5675 <3a3c46e2eff0577454860a203be1a8295f4acb76; version=b21d18b51b31a24d17f883b678432fbdee3d5675 <3e193ef4e0a3f5bf92ede83ef214cb09d01b00aa; version=b21d18b51b31a24d17f883b678432fbdee3d5675 <6c73fc931658d8cbc8a1714b326cb31eb71d16a7; version=b21d18b51b31a24d17f883b678432fbdee3d5675 <703dde112021c93d6e89443c070e7dbd4dea612e; version=b21d18b51b31a24d17f883b678432fbdee3d5675 <94cddf1e9227a171b27292509d59691819c458db; version=b21d18b51b31a24d17f883b678432fbdee3d5675 <abb4eff3dcd2e583060082a18a8dbf31f02689d4; version=b21d18b51b31a24d17f883b678432fbdee3d5675 <affbad02bf80380a7403885b9fe4a1587d1bb4f3; version=b21d18b51b31a24d17f883b678432fbdee3d5675 <bafe343a885c70dddf358379cf0b2a1c07355d8d

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

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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