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Threats / QNAP / CVE-2018-19943
CVE-2018-19943 · EUVD no mirror located · GCVE no mirror located Verified 2026-08-04

QNAP Network Attached Storage (NAS) vulnerability

Cross-site scripting vulnerability in QNAP NAS File Station allows remote attackers to inject malicious code, exploited in ransomware campaigns.

Verdict

Today item, not a backlog item.

XSS flaw in QNAP File Station enables code injection attacks. Active exploitation observed in ransomware operations targeting NAS devices. Affected systems require immediate patching to prevent compromise.

CISA KEV Yes · 2022-05-245Ransomware use Flagged5EPSS 0.17705 (verify live)6CVSS 83CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01

Is it exploitable?

— the evidence, ranked above the score
Reported exploitation
4 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
cybersecurityworks.com ↗cybersecurityworks.com ↗cisa.gov ↗go.recordedfuture.com ↗Confirmed
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-05-24), flagged for known ransomware use.
CISA KEV ↗Confirmed
Probability (EPSS)
EPSS 0.17705 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
FIRST EPSS ↗High
Severity / affected
CVSS 8 (CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H) · Affected: QNAP, Network Attached Storage (NAS). Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
CVE.org ↗Reported
Weakness (CWE)
Mapped to CWE-79 Cross-site Scripting (XSS), CWE-80 CWE-80 — weakness family: Web / client.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CVE.org ↗Reported
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
CISA-ADP ↗Reported
Currency of the record
CISA added this to its KEV catalog 573 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
CISA KEV ↗CVE.org ↗Reported
WeaknessCWE-79 · Cross-site Scripting (XSS)CWE-80 · CWE-80Web / client
02

Who’s exploiting it?

— attribution turns risk into urgency
Attribution not established

No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.

03

Why it matters

— the attack path, told twice: adversary, then board
1

Front door — unauthenticated access narrative 1

Attacker
I craft a malicious URL or upload content containing JavaScript that executes in the victim's browser when they access File Station.
Business
Attackers gain ability to steal session credentials or redirect users to phishing sites, compromising NAS access controls.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
I use the injected script to capture authentication tokens or manipulate file operations within the NAS interface.
Business
Unauthorized access to stored files and administrative functions increases risk of data theft or system compromise.
3

Lateral reach — past segmentation narrative 3

Attacker
I leverage the compromised NAS access to deploy ransomware payloads across the network or encrypt stored data.
Business
Ransomware deployment results in operational downtime, data loss, and extortion demands affecting business continuity.
04

What to do

— defensible action
  • Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05

Coverage & confidence

— what we know, and what we don’t

Established (cited)

  • KEV listing (CISA)
  • Ransomware-use flag (CISA)
  • EPSS probability (FIRST)
  • 4 reported-exploitation source(s)
  • CVSS 8 — CNA-assigned (CVE.org)
  • CISA SSVC triage disposition (CVE.org ADP)
  • CWE weakness mapping — CNA-assigned (CVE.org)
  • Catalogued by qnap (CNA)
  • Named finder/reporter credit (CVE.org)

    • Coverage gaps — stated, not hidden

  • No EUVD / GCVE mirror in feed — single-authority dependency for the identifier.
  • EPSS & exposure are time-varying; verify live at the source.
  • Threat-actor attribution not established from feed data — absence of a name is not absence of compromise.
    • Disclosure & credit2
    Catalogued by qnapCNA
    Credited with finding itIndependent Security Evaluatorsunspecified