CVE-2021-47607

Kernel-address disclosure via unchecked BPF CMPXCHG R0 pointer

Published Jun 19, 2024 · Updated May 11, 2026

Kernel address disclosure in Linux 5.12 through 5.15.10 allows local users to recover a kernel pointer via an unprivileged eBPF program. The BPF verifier fails to reject BPF_CMPXCHG instructions whose auxiliary R0 old-value register contains a pointer, allowing guessed addresses to be compared against a map slot. An unprivileged local account and enabled unprivileged BPF calls are required; successful probing discloses only a kernel address.

CVSS severityUnavailable
Unscored
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Kernel address disclosure in Linux 5.12 through 5.15.10 allows local users to recover a kernel pointer via an unprivileged eBPF program. The BPF verifier fails to reject BPF_CMPXCHG instructions whose auxiliary R0 old-value register contains a pointer, allowing guessed addresses to be compared against a map slot. An unprivileged local account and enabled unprivileged BPF calls are required; successful probing discloses only a kernel address.

The record

CVE
CVE-2021-47607
Published
Jun 19, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 19, 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=5.12
  2. Affected versionversion=5ffa25502b5ab3d639829a2d1e316cff7f59a41e <a82fe085f344ef20b452cd5f481010ff96b5c4cd
  3. Affected versionversion=5ffa25502b5ab3d639829a2d1e316cff7f59a41e <f87a6c160ecc8c7b417d25f508d3f076fe346136

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=5ffa25502b5ab3d639829a2d1e316cff7f59a41e <a82fe085f344ef20b452cd5f481010ff96b5c4cd; version=5ffa25502b5ab3d639829a2d1e316cff7f59a41e <f87a6c160ecc8c7b417d25f508d3f076fe346136

Published CVSS scores

No CVSS assessment is available in this record.

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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