CVE-2021-28798Network attack vector

File modification via undisclosed relative path traversal

Published May 21, 2021 · Updated Sep 16, 2024

Relative path traversal in QNAP QTS and QuTS hero allows remote attackers to modify files on affected NAS devices via network requests. QNAP has not disclosed the affected component or how relative path input escapes its intended directory. No privileges or user interaction are required under NVD's assessment, and successful exploitation compromises system integrity through file modification.

CVSS severity7.5
High
EPSS probability0.94%
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

Relative path traversal in QNAP QTS and QuTS hero allows remote attackers to modify files on affected NAS devices via network requests. QNAP has not disclosed the affected component or how relative path input escapes its intended directory. No privileges or user interaction are required under NVD's assessment, and successful exploitation compromises system integrity through file modification.

The record

CVE
CVE-2021-28798
Published
May 21, 2021
Updated
Sep 16, 2024
Vendor
Linn Products Limited
Product
QuTS hero
Classifications
CWE-23, CWE-284, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record 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=unspecified <h4.5.2.1638 Build 20210414

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Linn Products Limited · QuTS heroversion=unspecified <h4.5.2.1638 Build 20210414
Linn Products Limited · QTSversion=unspecified <4.3.3.1624 Build 20210416; version=unspecified <4.3.6.1663 Build 20210504; version=unspecified <4.5.2.1630 Build 20210406

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
8.8QNAP Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-23Relative Path Traversal
CWE-284Improper Access Control
T1190Exploit Public-Facing Application

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