CVE-2021-41864

Kernel memory corruption via stack-map allocation overflow

Published Oct 1, 2021 · Updated Aug 4, 2024

Out-of-bounds write in Linux kernel before 5.14.12 allows local users to crash the system via a crafted eBPF stack map. In prealloc_elems_and_freelist, a 32-bit elem_size wraps during multiplication by max_entries, so bpf_map_area_alloc reserves too little memory before pcpu_freelist_populate writes beyond the allocation. Reachability requires local ability to create the affected eBPF map; the confirmed result is kernel memory corruption that can terminate the system.

CVSS severity7.8
High
EPSS probability0.41%
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 write in Linux kernel before 5.14.12 allows local users to crash the system via a crafted eBPF stack map. In prealloc_elems_and_freelist, a 32-bit elem_size wraps during multiplication by max_entries, so bpf_map_area_alloc reserves too little memory before pcpu_freelist_populate writes beyond the allocation. Reachability requires local ability to create the affected eBPF map; the confirmed result is kernel memory corruption that can terminate the system.

The record

CVE
CVE-2021-41864
Published
Oct 1, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-190, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1499Endpoint Denial of Service

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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