CVE-2026-78587Network attack vectorHinoki check available

Agent upload interruption via unchecked session ownership

Published Sep 2, 2026 · Updated Sep 2, 2026

Incorrect authorization in Elastic Fleet Server allows remote authenticated users to interrupt other enrolled agents' multipart uploads. Multipart upload processing accepts an authenticated agent's session reference without verifying that the active session belongs to that agent. A valid enrolled-agent credential and another agent's active upload are required; affected releases can interrupt agent upload operations only.

CVSS severity3.1
Low
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Incorrect authorization in Elastic Fleet Server allows remote authenticated users to interrupt other enrolled agents' multipart uploads. Multipart upload processing accepts an authenticated agent's session reference without verifying that the active session belongs to that agent. A valid enrolled-agent credential and another agent's active upload are required; affected releases can interrupt agent upload operations only.

The record

CVE
CVE-2026-78587
Published
Sep 2, 2026
Updated
Sep 2, 2026
Vendor
Elastic
Product
Fleet Server
Classifications
CWE-863, CAPEC-122, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=8.0.0 <=8.19.15
  2. Affected versionversion=9.0.0 <=9.3.4
  3. Affected versionversion=9.4.0 <=9.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Elastic · Fleet Serverversion=8.0.0 <=8.19.15; version=9.0.0 <=9.3.4; version=9.4.0 <=9.4.1

Published CVSS scores

3.1ElasticCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
CAPEC-122Privilege Abuse
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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