CVE-2021-3489

Local kernel code execution via oversized ring-buffer reservation

Published Jun 4, 2021 · Updated Sep 16, 2024

Out-of-bounds write in affected Linux kernel 5.8-rc1 through 5.13-rc3 releases allows local users to execute kernel code through eBPF. The bpf_ringbuf_reserve() function accepts a reservation larger than its ring buffer, so writes to the returned region cross the allocated buffer boundary. Exploitation requires local low-privileged access and eBPF program execution; successful writes compromise the kernel, while failed attempts can crash the host.

CVSS severity7.8
High
EPSS probability0.55%
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 affected Linux kernel 5.8-rc1 through 5.13-rc3 releases allows local users to execute kernel code through eBPF. The bpf_ringbuf_reserve() function accepts a reservation larger than its ring buffer, so writes to the returned region cross the allocated buffer boundary. Exploitation requires local low-privileged access and eBPF program execution; successful writes compromise the kernel, while failed attempts can crash the host.

The record

CVE
CVE-2021-3489
Published
Jun 4, 2021
Updated
Sep 16, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-787, CWE-119, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=linux-5.10.y <v5.10.37
  2. Affected versionversion=linux-5.11.y <v5.11.21
  3. Affected versionversion=linux-5.12.y <v5.12.4
  4. Affected versionversion=trunk <v5.13-rc4
  5. Affected versionversion=v5.8 <5.8*

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=linux-5.10.y <v5.10.37; version=linux-5.11.y <v5.11.21; version=linux-5.12.y <v5.12.4; version=trunk <v5.13-rc4; version=v5.8 <5.8*

Published CVSS scores

7.8Canonical Ltd.CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/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.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1068Exploitation for Privilege Escalation

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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