CVE Intelligence
Low Denial of service

CVE-2021-21296 — Denial-of-service in Fleet

Fleet is an open source osquery manager. In Fleet before version 3.7.0 a malicious actor with a valid node key can send a badly formatted request that causes the Fleet server to exit, resulting in denial of service. This is possible only while a live query is currently ongoing. We believe the impact of this vulnerability to be low given the requirement that the actor has a valid node key. There is no information disclosure, privilege escalation, or code execution. The issue is fixed in Fleet 3.7.0.

Published Feb 10, 2021 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

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 1.9% (30-day exploitation probability)+12

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
1.94%
ahead of 80% of scored CVEs · Oct 14, 2026
Affects
Fleetdm
Fleet
CVSS base
2.7
Low · 3 source(s)

Remediation

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

  • Documented patch — github.com (NIST National Vulnerability Database)

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 (Fleetdm Fleet).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Fleetdm Fleet < 3.7.0 Vulnerable NIST National Vulnerability Database
Fleetdm Fleet version < 3.7.0 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

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

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

Every base score collected

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

ScoreVersionSeverityExpl.ImpactScored by
2.7 CVSS 3.1 Low 1.2 1.4 security-advisories@github.com via NIST National Vulnerability Database
2.7 CVSS 3.1 Low 1.2 1.4 nvd@nist.gov via NIST National Vulnerability Database
2.7 CVSS 3.1 Low — — GitHub_M via CVE Program (cve.org) e CISA ADP
4.0 CVSS 2.0 Medium 8.0 2.9 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-400 · Uncontrolled Resource Consumption

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 1.94%

Detection

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

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Track CPU/memory spikes and availability drops correlated with request patterns.
web/proxy/WAF logsnetwork IDS/IPSresource metrics

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · fleetdm/fleet
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • Fix documented
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVSS changed · 2.7
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • 2021
  • CVE published
    Feb 10, 2021 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

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

References

3 on the record

Elsewhere on this site

Fleetdm
every CVE for this vendor
Denial of service
same class
CWE-400
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-103264 Fleet before 4.87.0 Authentication Bypass via Device Identifiers 14d
  • CVE-2026-103265 Fleet before 4.89.0 Information Disclosure via MDM Command Results 14d
  • CVE-2026-101047 Fleet before 4.87.0 Unauthenticated iOS App Download via Predictable URLs 18d
  • CVE-2026-101046 Fleet before 4.89.0 SQL Injection via ORDER BY Activity Endpoints 18d
  • CVE-2026-101045 Fleet Homebrew Cask OS Command Injection via Metadata 18d
  • CVE-2026-54245 Fleet: SQL injection in Okta conditional access endpoint allows host-controlled compromise of the Fleet database Aug 26, 2026

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 CISA SSVC assessment.
  • 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-2021-21296 is "Denial-of-service in Fleet", rated Low. It affects Fleet (Fleetdm); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 2.7 describes technical severity. EPSS 1.94% 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.