CVE Intelligence
High Memory corruption

CVE-2021-34866 — This vulnerability allows local attackers to escalate privileges on affected installations of...

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.

Published Jan 25, 2022 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: zdi

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 1% (30-day exploitation probability)+9
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.97%
ahead of 61% of scored CVEs · Oct 14, 2026
Affects
Linux
Linux Kernel and 8 more
CVSS base
7.8
High · 4 source(s)
Prioritization reference: 8.8 provisional

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux Kernel, Netapp H300e Firmware, Netapp H300s Firmware…).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux Kernel ≥ 5.8 and < 5.10.62≥ 5.11 and < 5.13.14 Vulnerable NIST National Vulnerability Database
Linux Linux Kernel version 5.14-rc3 Vulnerable CVE Program (cve.org) e CISA ADP
Netapp H300e Firmware versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp H300s Firmware versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp H410c Firmware versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp H410s Firmware versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp H500e Firmware versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp H500s Firmware versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp H700e Firmware versions not specified by the source Vulnerable NIST National Vulnerability Database
Netapp H700s Firmware versions not specified by the source Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.8 CVSS 3.1 High 1.8 5.9 nvd@nist.gov via NIST National Vulnerability Database
7.8 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
8.8 CVSS 3.0 High 2.0 6.0 zdi-disclosures@trendmicro.com via NIST National Vulnerability Database
8.8 CVSS 3.0 High — — zdi via CVE Program (cve.org) e CISA ADP
7.2 CVSS 2.0 High 3.9 10.0 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 8.8 (zdi-disclosures@trendmicro.com via NIST National Vulnerability Database) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-843 · Type Confusion

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.97%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · linux/kernel
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 7.8
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • 2022
  • CVE published
    Jan 25, 2022 · zdi

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 13, 2026 – Oct 13, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

6 on the record

Elsewhere on this site

Linux
every CVE for this vendor
Memory corruption
same class
CWE-843
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-98164 KVM: x86/mmu: Check write tracking in all address spaces 16d
  • CVE-2026-98163 cgroup: Avoid iteration of dying tasks with zero refcount 19d
  • CVE-2026-98162 smb/server: fix tree connection leak in smb2_tree_connect() 20d
  • CVE-2026-98160 In the Linux kernel, the following vulnerability has been resolved: staging: rtl8723bs… 20d
  • CVE-2026-98161 Improper Check for Unusual or Exceptional Conditions in Linux Linux Kernel 20d
  • CVE-2026-100079 Missing Release of Resource after Effective Lifetime in Linux Linux Kernel 20d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2021-34866 is "This vulnerability allows local attackers to escalate privileges on affected installations of...", rated High. It affects Linux Kernel (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. EPSS 0.97% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.

Sign in or create an account to comment and suggest corrections.