CVE-2018-19953
If exploited, this cross-site scripting vulnerability could allow remote attackers to inject malicious code. QNAP has already fixed the issue in the following QTS versions. QTS 4.4.2.1231 on build 20200302; QTS 4.4.1.1201 on build 20200130; QTS 4.3.6.1218 on build 20200214; QTS 4.3.4.1190 on build 20200107; QTS 4.3.3.1161 on build 20200109; QTS 4.2.6 on build 20200109.
- CVSS
- 6.1Mediumscored by CISA
- Exploited in the wild
- Yes, in CISA KEV since 24 May 2022CISA deadline for US federal agencies: 14 Jun 2022known use in ransomware campaigns
- EPSS
- 30.5%chance of exploitation in the next 30 daystop 2% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 28 Oct 2020analysed here 12 Nov 2026
Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)
Summary
Triage
- Attack surface
- Client-side
- Exploitable
- At runtime
- Attack vector
- network
- Can a WAF block it?
- Yes. See why
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
| Product | Affected versions | Vendor says fixed in |
|---|---|---|
| QNAP Systems Inc. QTS | < 4.4.2.1231< 4.4.1.1201< 4.3.6.1218< 4.3.4.1190< 4.3.3.1161< 4.2.6Vendor says fixed in: not stated |
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
Products named in our analysis
- qnap:qts
Fix and mitigation
WAF and other mitigations
Can a WAF block it? Yes. Cross-site scripting sends script tags or event handlers in the request, which WAF signatures match well.
Also consider: CSP · output encoding
Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Listed since 24 May 2022. Known use in ransomware campaigns.
- CISA due date
- 14 Jun 2022, the remediation deadline for US federal agencies
- CISA required action
- Apply updates per vendor instructions.
- Public exploit code
- None on record in Exploit-DB, Metasploit, Nuclei templates or PoC-in-GitHub.
- CISA SSVC
- exploitation active, automatable no, technical impact totalAssessed by CISA 13 Aug 2026 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
Timeline
- 28 Oct 2020Published
- 24 May 2022Added to CISA KEV (exploited in the wild)572 days (about 2 years) later
- 14 Jun 2022CISA remediation due date (US federal agencies)21 days later
- 13 Aug 2026CISA SSVC assessment: exploitation active1,521 days (about 4 years) later
- 1 Oct 2026CVE record last updated50 days later
- 12 Nov 2026Analysed by vulneraibility.com42 days later
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
| Metric | Value | What it means |
|---|---|---|
| Attack vector | NetworkReachable over the internet or any routable network. | Reachable over the internet or any routable network. |
| Attack complexity | LowRepeatable attack, no special conditions. | Repeatable attack, no special conditions. |
| Privileges required | NoneThe attacker needs no prior access. | The attacker needs no prior access. |
| User interaction | RequiredA victim must click, open or otherwise cooperate. | A victim must click, open or otherwise cooperate. |
| Scope | ChangedImpact crosses a security boundary into other components. | Impact crosses a security boundary into other components. |
| Confidentiality | LowPartial data disclosure. | Partial data disclosure. |
| Integrity | LowLimited modification possible. | Limited modification possible. |
| Availability | NoneThe service stays up. | The service stays up. |
Common questions
Is CVE-2018-19953 being exploited?
Yes. CVE-2018-19953 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2018-19953?
CVE-2018-19953 is rated Medium with a CVSS score of 6.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2018-19953?
Yes. A fix has been recorded for CVE-2018-19953. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2018-19953 affect?
CVE-2018-19953 affects qnap:qts. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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