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Security report for zerossl.com

ZeroSSL · Technology · N/a

Medium risk. 5 critical or high findings in Security headers and SSL/TLS.

Security score

73/100

Risk levelMedium

0–100, higher is better. How it is calculated

ZeroSSL is a technology company specializing in providing free and automated SSL certificates to website owners, developers, and enterprises. The company positions itself as a trusted certificate authority with a strong market presence, supported by notable industry clients such as Microsoft, Intel, and Hubspot. Their services include SSL certificate issuance, monitoring, one-step validation, quick installation, and ACME automation, catering to a broad audience seeking reliable and fast SSL solutions. Founded in 2016, ZeroSSL has established a medium-sized operation with consistent branding and a professional online presence. Technically, the website leverages a modern technology stack including jQuery, Google Tag Manager, Google Analytics, and Cookiebot for cookie consent management. Hosting and DNS services are provided via Cloudflare, enhancing performance and security. The site demonstrates good mobile optimization, SEO practices, and basic accessibility features, though there is room for improvement in accessibility and security headers. From a security perspective, ZeroSSL enforces HTTPS and employs domain registration protections such as clientDeleteProhibited and clientTransferProhibited statuses. Cookie consent is managed comprehensively with granular user controls, reflecting good privacy compliance. However, DNSSEC is not enabled, and explicit security policies or incident response contacts are not publicly available, representing areas for enhancement. Overall, the website is professional, trustworthy, and secure, with no indications of malicious content or vulnerabilities. The domain registration details align well with the business claims, supporting legitimacy. Strategic recommendations include enabling DNSSEC, publishing a security.txt file, enhancing HTTP security headers, and providing clearer contact information for security incidents.

Scanned

NIS2 and GDPR posture

GDPR outside view
83/ 100 · Low
Checks completed
7of 7

NIS2 Art. 21(2)

  1. (a) Risk analysis and security policies: Not visible from outside
  2. (b) Incident handling: One indicator
  3. (c) Business continuity, backups and crisis management: Not visible from outside
  4. (d) Supply chain security: Not visible from outside
  5. (e) Secure acquisition, development and maintenance, including vulnerability handling: Partly checked
  6. (f) Assessing the effectiveness of security measures: Not visible from outside
  7. (g) Cyber hygiene and security training: Not visible from outside
  8. (h) Cryptography and encryption: Partly checked
  9. (i) HR security, access control and asset management: One indicator
  10. (j) Multi-factor authentication and secured communications: Not visible from outside

This scan rated NIS2 with an earlier keyword method that is no longer shown; rescan for the per-article view. Risk management, continuity, supply chain, training, MFA, management oversight (Art. 20) and incident reporting (Art. 23) need internal evidence, and Guard cannot tell whether NIS2 applies to this organisation.

GDPR is indicative only, based on publicly visible signals: Articles 7, 12, 13 and 32 of Regulation (EU) 2016/679 and Article 5(3) of the ePrivacy Directive. Not a certification or legal assessment.

Priority findings

5 findings rated critical or high. Fix these first.

  1. Security headers

    Security headers are instructions your web server sends to every visitor’s browser. Missing ones leave visitors more exposed to attacks such as clickjacking and injected scripts.

    • High

      Missing Strict-Transport-Security header

      Forces HTTPS connections

      What to do: Add "Strict-Transport-Security: max-age=31536000; includeSubDomains; preload"

      • CWE-319
      • OWASP A04:2025
      • ASVS V3.4.1
    • High

      Missing X-Frame-Options header

      Prevents clickjacking attacks

      What to do: Add "X-Frame-Options: DENY" or "X-Frame-Options: SAMEORIGIN"

    • High

      Missing Content-Security-Policy header

      Controls resources the browser is allowed to load

      What to do: Implement a Content-Security-Policy appropriate for your application

      • ASVS V3.4.3
      • OWASP Secure Headers: OWASP Secure Headers Project recommends Content-Security-Policy: default-src 'self'; form-action 'self'; base-uri 'self'; object-src 'none';…

  2. SSL/TLS

    TLS encrypts the connection and proves the site is really yours. Weak or expiring certificates trigger browser warnings and put traffic at risk.

    • High

      Weak Protocols Supported

      Server supports weak protocols: TLSv1.1

      What to do: Disable TLS 1.0, TLS 1.1, and all SSL versions

      • CWE-327
      • OWASP A04:2025
      • ASVS V12.1.1
    • High

      Weak SSL Key Length

      SSL certificate uses 256-bit key, which is considered weak

      What to do: Use at least 2048-bit RSA or 256-bit ECC key

      • CWE-326
      • OWASP A04:2025
      • Mozilla TLS: Mozilla Server Side TLS 6.0 intermediate: rsa_key_size 2048

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  • TLS certificates and expiry
  • DNS records
  • SPF, DKIM and DMARC
  • Security headers
  • GDPR and NIS2 posture
  • Exposed services
  • Third-party trackers
  • Security score drift

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Results by check

Each check with its score, findings and the evidence it collected.

How this score is calculated

The security score runs 0–100, higher is better. It is the plain average of the security checks that completed in this scan, each counted equally. A check that could not run is left out: it counts neither as a pass nor as a fail.

Counted in this score

SSL/TLS
57
Security headers
15
Email security
100
DNS health
85
Network security
100
GDPR outside view
83
Average
73

Not counted

  • NIS2 outside view: Re-weights evidence from the TLS, email, DNS, network and hygiene checks, so counting it would count that evidence twice. Shown on its own.
  • OffSeq Observations: An AI reading of the site, useful context but not reproducible evidence. Shown on its own.

Findings that cap the score at 49

Each of these is serious on its own, so while any is present the site cannot rate better than high risk, however good the other checks are.

  • The certificate is not trusted by browsers
  • The website is not served over HTTPS
  • A database, remote desktop, file-sharing or Telnet service is reachable from the internet
  • The page loads a script from a compromised source
  • The domain registration has expired
  • SPF authorises every server to send mail as the domain

Partial scans

When the site blocks Guard or most checks cannot run, the score covers only the checks that ran (usually DNS and email), is capped at 75 and is shown as partial, without a risk level.

Risk levels

  • Critical0–25
  • High26–49
  • Medium50–75
  • Low76–100

Technical appendix

Business context, site observations and technical notes gathered during the scan, and the standards behind each reference.

Business context

Business profile

ZeroSSL operates in the competitive SSL certificate authority market, offering free and paid SSL certificates with automation capabilities. Their business model focuses on simplifying SSL management through REST APIs and ACME protocol support, targeting developers and enterprises. The company leverages partnerships and related domains to extend service offerings and support. Their market positioning is strengthened by endorsements from leading technology companies and a clear focus on ease of use and automation. Revenue streams likely include premium SSL certificates and enterprise services. Growth indicators include continuous feature additions and a robust partner ecosystem. Strategic observations highlight the importance of maintaining trust through transparent privacy practices and strong security postures.

Security posture

ZeroSSL demonstrates a mature security posture with enforced HTTPS, domain registration protections, and comprehensive cookie consent management. The use of Cookiebot ensures GDPR compliance and user privacy controls. However, the absence of DNSSEC and lack of published security policies or incident response contacts are notable gaps. No exposed sensitive data or vulnerable libraries were detected in the analyzed content. The website uses modern analytics and marketing tools responsibly with transparent disclosures. Overall, the security culture appears proactive but could benefit from formalizing vulnerability disclosure processes and enhancing HTTP security headers.

Recommendations

  1. Enable DNSSEC to strengthen DNS security and prevent spoofing.
  2. Publish a security.txt file to facilitate vulnerability reporting and improve incident response.
  3. Implement additional HTTP security headers such as Content Security Policy (CSP), Strict-Transport-Security (HSTS), and X-Frame-Options.
  4. Provide explicit security policy and incident response contact information on the website.
  5. Regularly audit and update third-party libraries and scripts to mitigate potential vulnerabilities.
Site observations

Automated reading of the public site. Ratings are indicative.

Business

Company
ZeroSSL
Description
Free SSL certificates issued instantly online, supporting ACME clients, SSL monitoring, quick validation and automated SSL renewal via ZeroSSL Bot or REST API.
Key services
Free SSL Certificates, SSL Monitoring, One-Step Validation, Quick Installation, Management Console, ACME Automation, Enterprise SSL
Content quality
good
Branding
consistent

Technology

Stack
jQuery 1.11.3, Google Tag Manager, Google Analytics, Cookiebot, Trustpilot widget, Cloudflare DNS
Performance
moderate
Mobile
good
Accessibility
basic
SEO
good

Security

Observed score
85/100
Good practices seen
  • HTTPS enforced
  • Domain status includes clientDeleteProhibited, clientRenewProhibited, clientTransferProhibited, clientUpdateProhibited
  • Cookie consent with granular controls
  • No DNSSEC enabled (recommend enabling)

Analytics and tracking

Services
Google Analytics, Ahrefs Analytics
Tracking level
extensive
Privacy practices
good

Advertising

Ad networks
Google DoubleClick, Google AdSense
Tracking pixels
Cookiebot, Pingdom
Marketing tools
Trustpilot widget, Cookiebot
Transparency
good

Site quality

Design
good
User experience
good
Content relevance
good
Navigation
good
Professionalism
good
Trustworthiness
high

Key observations

  1. Website offers free and paid SSL certificate services with automation features.
  2. Strong cookie consent management via Cookiebot with detailed cookie declarations.
  3. Multiple trusted industry clients showcased as trust signals.
  4. No direct contact emails or phone numbers found on the homepage or visible content.
  5. No explicit privacy or security policy pages found on main domain but privacy policy linked via Cookiebot.
  6. Use of modern analytics and marketing tools with transparent cookie usage.
  7. No signs of malicious or suspicious content or domains.
  8. Domain registration is stable and consistent with business operations.
Technical notes

Notes

The website is built on a stable and widely supported technology stack including jQuery and Google Tag Manager, with Cloudflare providing DNS and likely CDN services. Performance is moderate with good mobile responsiveness and SEO optimization. Accessibility is basic and could be improved to meet higher standards. The site uses asynchronous loading for analytics and consent scripts, enhancing load times. There is no detected CMS, suggesting a custom or static site architecture. Technical risks are minimal but include the lack of DNSSEC and incomplete security header implementation. Opportunities exist to modernize accessibility and security features to further enhance user trust and compliance.
Standards and sources

Reference chips under each finding point to the standard, regulation or specification the finding relates to. They are taken from the official datasets below and mapped conservatively: a finding with no defensible link shows none. NIS2 and GDPR references mark where a finding is relevant evidence, not a compliance verdict. Implementing Regulation (EU) 2024/2690 binds digital infrastructure and digital service providers; for other entities it is the most detailed public reading of the Article 21 measures. WCAG, EN 301 549, European Accessibility Act and Web Accessibility Directive references name the requirement an automated accessibility rule relates to; they are not a conformance verdict.

Retrieved 2026-10-25

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