Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-34866

CVE-2021-34866HIGH

Linux Kernel — This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel 5.14-rc3.

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   L   L   N  U  H  H  H    7.8   .0097   61.3     —

AFFECTED
  Product  Versions    Fixed
  Kernel   5.14-rc3 –  —

TIMELINE
  Jun 17  Reserved by zdi
  Jan 25  Published (CNA: zdi)
  Oct 8   RESCORED — CVE-2021-34866 (Linux Kernel). CVSS 8.8 → 7.8 (NVD).

CWE-843 · CNA: zdi · CVSS v3.1 · 2 references · NVD status: Modified

Description

This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel 5.14-rc3. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the handling of eBPF programs. The issue results from the lack of proper validation of user-supplied eBPF programs, which can result in a type confusion condition. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the kernel. Was ZDI-CAN-14689.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
June 17, 2021	Reserved	Reserved by zdi
January 25, 2022	Published	Published (CNA: zdi)
October 8, 2026	RESCORED	RESCORED — CVE-2021-34866 (Linux Kernel). CVSS 8.8 → 7.8 (NVD).

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
Linux	Kernel	—	5.14-rc3	—

Weaknesses

CWE-843

References (2)

https://security.netapp.com/advisory/ntap-20220217-0008/ [Third Party Advisory]
https://www.zerodayinitiative.com/advisories/ZDI-21-1148/ [Third Party Advisory, VDB Entry]

Authoritative record: CVE-2021-34866 at cve.org

Vendors: linux

Weaknesses: CWE-843

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-34866 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.