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Quts HeroOperating system · Qnap

CVE-2025-53591

MEDIUM · 6.5 CVSS v3.1 Published 2026-01-02
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A use of externally-controlled format string vulnerability has been reported to affect several QNAP operating system versions. If a remote attacker gains an administrator account, they can then exploit the vulnerability to obtain secret data or modify memory. We have already fixed the vulnerability in the following versions: QTS 5.2.7.3256 build 20250913 and later QuTS hero h5.2.7.3256 build 20250913 and later QuTS hero h5.3.1.3250 build 20250912 and later

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A format string vulnerability in QNAP QTS and QuTS hero operating systems allows an authenticated remote attacker with administrator privileges to exploit externally-controlled format strings, potentially exposing secret data or corrupting memory.

MitigationUpdate affected QNAP devices to QTS 5.2.7.3256 build 20250913, QuTS hero h5.2.7.3256 build 20250913, or QuTS hero h5.3.1.3250 build 20250912 or later versions.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Quts HeroOperating system
Affected:= h5.2.0.2737= h5.2.0.2782= h5.2.0.2789= h5.2.0.2802= h5.2.0.2823= h5.2.0.2851= h5.2.0.2860= h5.2.1.2929= h5.2.1.2940= h5.2.2.2952= h5.2.3.3006= h5.2.4.3070
QtsOperating system
Affected:= 5.2.0.2737= 5.2.0.2744= 5.2.0.2782= 5.2.0.2802= 5.2.0.2823= 5.2.0.2851= 5.2.0.2860= 5.2.1.2930= 5.2.2.2950= 5.2.3.3006= 5.2.4.3070= 5.2.4.3079

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the QNAP operating system type
    Log into the QNAP device admin console and look at the main dashboard or go to Control Panel > System > Firmware to determine if the device is running QTS or QuTS hero
    Affected if The device is running QuTS hero (hybrid mode) or standard QTS firmware
  2. Check the installed QTS or QuTS hero version
    Navigate to Control Panel > System > Firmware or System Settings > About, and note the exact version number shown (e.g., 5.2.0.2737 or h5.2.1.2929)
    Affected if The displayed version matches any of the versions listed in the affected versions list for the respective OS
  3. Compare installed version against affected ranges
    Match the exact version number found (including build number if visible) against the specific versions: for QuTS hero: h5.2.0.2737, h5.2.0.2782, h5.2.0.2789, h5.2.0.2802, h5.2.0.2823, h5.2.0.2851, h5.2.0.2860, h5.2.1.2929, h5.2.1.2940, h5.2.2.2952, h5.2.3.3006, h5.2.4.3070; for QTS: 5.2.0.2737, 5.2.0.2744, 5.2.0.2782, 5.2.0.2802, 5.2.0.2823, 5.2.0.2851, 5.2.0.2860, 5.2.1.2930, 5.2.2.2950, 5.2.3.3006, 5.2.4.3070, 5.2.4.3079
    Affected if The installed version exactly matches one of the listed affected versions
  4. Verify administrator access exposure
    Determine if the QNAP admin interface is accessible externally (via WAN/Internet) or if the device has admin accounts with weak or compromised credentials
    Affected if The QNAP device admin interface is exposed to untrusted networks or admin credentials may be compromised, allowing authenticated attacker access

The environment is affected if the device runs QuTS hero or QTS with a version number that exactly matches one of the listed affected versions and an attacker could obtain administrator-level access to the device.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update affected QNAP devices to QTS 5.2.7.3256 build 20250913, QuTS hero h5.2.7.3256 build 20250913, or QuTS hero h5.3.1.3250 build 20250912 or later versions.

Recommended fix High confidence

QTS 5.2.7.3256 build 20250913 or later; QuTS hero h5.2.7.3256 build 20250913 or h5.3.1.3250 build 20250912 or later

  1. Log in to the QNAP admin interface as administrator
  2. Navigate to Control Panel > System > Firmware Update
  3. Check for updates or manually download and upload the firmware for your model
  4. Update to QTS 5.2.7.3256 (build 20250913) or later, OR QuTS hero h5.2.7.3256 (build 20250913) / h5.3.1.3250 (build 20250912) or later depending on your system
  5. Verify the firmware version after update to confirm successful installation
Caveat Review QNAP release notes for your specific model before upgrading, as firmware updates may include configuration changes or feature modifications

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Quts Hero Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-53591 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data