CVE-2021-46974

Kernel memory disclosure and crash via mis-masked offsets

Published Feb 27, 2024 · Updated Aug 5, 2026

Spectre v1 pointer-sanitization failure in affected Linux kernel versions allows local users to disclose kernel memory or crash the host. In kernel/bpf/verifier.c, the verifier reverses pointer arithmetic incorrectly when a negative offset register is the destination, producing an invalid mask and wild pointer. Reachability requires low-privileged local access with unprivileged BPF enabled; a crafted socket-filter or cgroup-skb program can leak memory through a side channel or panic the kernel.

CVSS severity7.1
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Spectre v1 pointer-sanitization failure in affected Linux kernel versions allows local users to disclose kernel memory or crash the host. In kernel/bpf/verifier.c, the verifier reverses pointer arithmetic incorrectly when a negative offset register is the destination, producing an invalid mask and wild pointer. Reachability requires low-privileged local access with unprivileged BPF enabled; a crafted socket-filter or cgroup-skb program can leak memory through a side channel or panic the kernel.

The record

CVE
CVE-2021-46974
Published
Feb 27, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 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=078da99d449f64ca04d459cdbdcce513b64173cd
  2. Affected versionversion=4.14.113 <4.14.233
  3. Affected versionversion=4.19.19 <4.19.190
  4. Affected versionversion=4.20.6 <4.21
  5. Affected versionversion=5.0
  6. Affected versionversion=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <2cfa537674cd1051a3b8111536d77d0558f33d5d
  7. Affected versionversion=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <53e0db429b37a32b8fc706d0d90eb4583ad13848
  8. Affected versionversion=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <6eba92a4d4be8feb4dc33976abac544fa99d6ecc
  9. Affected versionversion=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <7cf64d8679ca1cb20cf57d6a88bfee79a0922a66
  10. Affected versionversion=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <b9b34ddbe2076ade359cd5ce7537d5ed019e9807
  11. Affected versionversion=ae03b6b1c880a03d4771257336dc3bca156dd51b <4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba
  12. Affected versionversion=f92a819b4cbef8c9527d9797110544b2055a4b96 <0e2dfdc74a7f4036127356d42ea59388f153f42c

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=078da99d449f64ca04d459cdbdcce513b64173cd; version=4.14.113 <4.14.233; version=4.19.19 <4.19.190; version=4.20.6 <4.21; version=5.0; version=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <2cfa537674cd1051a3b8111536d77d0558f33d5d; version=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <53e0db429b37a32b8fc706d0d90eb4583ad13848; version=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <6eba92a4d4be8feb4dc33976abac544fa99d6ecc; version=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <7cf64d8679ca1cb20cf57d6a88bfee79a0922a66; version=979d63d50c0c0f7bc537bf821e056cc9fe5abd38 <b9b34ddbe2076ade359cd5ce7537d5ed019e9807; version=ae03b6b1c880a03d4771257336dc3bca156dd51b <4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba; version=f92a819b4cbef8c9527d9797110544b2055a4b96 <0e2dfdc74a7f4036127356d42ea59388f153f42c

Published CVSS scores

2.3Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
7.1Linux Kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
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

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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