CVE-2026-3091

Arbitrary file access via installer DLL side-loading

Published Feb 24, 2026 · Updated Feb 24, 2026

Uncontrolled DLL search in Synology Presto Client before 2.1.3-0672 allows local users to read or write arbitrary files during installation. The Windows installer searches its own directory for a DLL and loads an attacker-planted copy from that location. Exploitation requires advance local placement and user interaction; the published denial-of-service impact has no specified interruption type.

CVSS severity6.7
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Uncontrolled DLL search in Synology Presto Client before 2.1.3-0672 allows local users to read or write arbitrary files during installation. The Windows installer searches its own directory for a DLL and loads an attacker-planted copy from that location. Exploitation requires advance local placement and user interaction; the published denial-of-service impact has no specified interruption type.

The record

CVE
CVE-2026-3091
Published
Feb 24, 2026
Updated
Feb 24, 2026
Vendor
Synology
Product
Synology Presto Client
Classifications
CWE-427, CAPEC-471, T1574.002
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 24, 2026Record 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=* <2.1.3-0672

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Synology · Synology Presto Clientversion=* <2.1.3-0672

Published CVSS scores

6.7Synology Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
7.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-427Uncontrolled Search Path Element
CAPEC-471Search Order Hijacking
T1574.002Hijack Execution Flow: DLL Side-Loading

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo