SecurinZero Days
    Email Us
    Zero-Day Research/CVE-2015-9539
    ▲ MediumCVSS 6.1✓ PatchedEPSS 0.00462%

    Reflected XSS in Fast Secure Contact Form

    The Fast Secure Contact Form plugin before 4.0.38 for WordPress allows fs_contact_form1[welcome] XSS.

    CVE IDCVE-2015-9539
    CVSS v3.16.1 Medium
    VendorFast Secure
    CWECWE-79
    DisclosedSep 7, 2015
    StatusFixed
    All advisories
    • 01Description
    • 02Proof of Concept
    • 03Impact
    • 04Remediation
    • 05Timeline
    • 06References
    01/Description

    What this actually is.

    Technical background, root cause, and affected surface.

    A Cross-Site Scripting vulnerability was identified in WordPress plugin Fast Secure Contact Form before 4.0.37 in fs_contact_form1[welcome].  

    Vendor
    Fast Secure
    Affected Product
    Fast Secure Contact Form
    CVE
    CVE-2015-9539
    Securin ID
    2015-CSW-09-1007
    Status
    Fixed
    Date
    September 7, 2015
    Severity
    Medium
    CVSS Score
    6.1
    Vector
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    CWE
    CWE-79
    02/Proof of Concept

    From one request
    to root shell.

    Reproduced in a sandboxed environment. Requires only LAN or WiFi adjacency.

    6.1CVSS 3.1
    VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    ScopeChanged
    ImpactC:L / I:L / A:N
    SeverityMedium
    PoC · Exploitation Steps▲ trigger
    01Visit the following page on a site with this plugin installed.02http://yourwordpresssite.com/wordpress/wpadmin/plugins.php?page=sicontactform%2Fsi-contact-form.php&fscf_form=1&fscf_tab=1 and modify the value of fs_contact_form1[welcome] variable with <script>alert(document.cookie);</script> payload and send the request to the server. Now, the added XSS payload is echoed back from the server without validating the input whenever we visit the script stored page.03Note: XSS payload has been tried with the application once after implementing Unfiltered Html Settings as defined to the wp-config.php file.04define( ‘DISALLOW_UNFILTERED_HTML’, true );05Issue: POST request parameter fs_contact_form1[welcome] variable in the given URL http://yourwordpresssite.com/wordpress/wpadmin/plugins.php?page=sicontactform%2Fsi-contact-form.php&fscf_form=1&fscf_tab=1 of Fast Secure Contact Form 4.0.37 is vulnerable to Cross-Site Scripting (XSS).06Figure 01: http://yourwordpresssite.com/wordpress/wp-admin/plugins.php?page=si-contact-form%2Fsi-contact-form.php&fscf_form=1&fscf_tab=107Figure 02: XSS Payload is executed in the browser whenever the user views it.
    03/Impact

    What an attacker does to you.

    Post-exploitation outcomes mapped to CVSS impact metrics.

    An attacker can inject malicious code into the applications via a vulnerable variable.

    04/Remediation

    Fix it. In this order.

    A runbook, not a checklist. Sequence matters — assume compromise before you act.

    Download the latest updated version of the Nextgen plugin and apply the patch as per vendor advisory.

    Securin advisory — For coordinated remediation support or threat-actor briefings related to CVE-2015-9539, contact disclose@securin.io
    05/Disclosure Timeline

    Vendors moved in days.
    Attackers in hours.

    Reconstructed from vendor advisories, CISA bulletins, and Securin research records.

    Sep 05, 2015

    Discovered in Fast Secure Contact Form plugin 4.0.37 Version.

    Sep 07, 2015

    Reported to WP Plugin.

    Sep 07, 2015

    WP acknowledged the issue.

    Sep 08, 2015

    Fixed in 4.0.38 version of Fast Secure Contact Form plugin.

    Timeline recorded · Disclosure coordinated by Securin

    06/References

    Cite, verify, go deeper.

    Primary sources — NVD, CISA KEV, and machine-readable IoC feed.

    NVD

    NVD — CVE-2015-9539

    nvd.nist.gov/vuln/detail/CVE-2015-9539 →
    SEC

    Securin VI — Full Technical Analysis

    vi.securin.io →

    Let Securin level up your security posture.

    Get a live exposure assessment, threat-actor briefing tailored to your sector, and IoC mapping for your SIEM.

    Browse all advisories
    SecurinSecurinZero Days

    Securin's zero-day research operation combines frontier AI models with a decade of offensive expertise — discovering, validating, and coordinating the disclosure of high-impact vulnerabilities at a scale and speed no human team achieves alone.

    Glossary
    © 2026 Securin Inc · CVE Numbering Authority
    Privacy Policy·Data Processing Addendum