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Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-3347

MEDIUM · 5.5 CVSS v3.1 Published 2026-03-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
61/100
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
The Multi Functional Flexi Lightbox plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `arv_lb[message]` parameter in all versions up to, and including, 1.2 due to insufficient input sanitization and output escaping. This is due to the `arv_lb_options_val()` sanitize callback returning user input without any sanitization, and the stored `message` value being output in the `genLB()` function without escaping. This makes it possible for authenticated attackers, with Administrator-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses a page or post with the lightbox enabled.

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

The Multi Functional Flexi Lightbox WordPress plugin up to version 1.2 contains a stored XSS vulnerability in the `arv_lb[message]` parameter. The plugin's settings save callback `arv_lb_options_val()` fails to sanitize user input, and the `genLB()` function outputs the stored message value without escaping, allowing injected scripts to execute on any page where the lightbox is loaded.

MitigationUpdate the plugin to a patched version once available, or manually add `sanitize_text_field()` in the `arv_lb_options_val()` callback and apply `esc_html()` or `esc_attr()` when outputting the message in `genLB()`. Review all other settings parameters for similar sanitization issues.

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

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
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/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. Confirm plugin installation and version
    In WordPress admin, go to Plugins > Installed Plugins and look for 'Multi Functional Flexi Lightbox', or check the plugin main file header for the 'Version' comment. Alternatively, search the wp-content/plugins directory for a folder containing 'flexi' or 'lightbox' in the name.
    Affected if The plugin is installed and its version is 1.2 or lower (the summary indicates versions up to 1.2 are affected).
  2. Locate the vulnerable settings callback
    In the plugin directory, search for the function named 'arv_lb_options_val' or 'arv_lb_options_val()' within PHP files. Inspect the function to see if it applies any sanitization (such as sanitize_text_field, sanitize_html_class, or similar) to the arv_lb[message] input before saving.
    Affected if The function exists and performs no sanitization on the arv_lb[message] parameter before saving it to the database.
  3. Locate the vulnerable output function
    In the plugin directory, search for the function named 'genLB' or 'genLB()'. Inspect how it handles the stored message value - look for whether it uses escaping functions like esc_html(), esc_attr(), or similar when outputting the message.
    Affected if The function outputs the message value without escaping (no esc_html(), esc_attr(), or similar function wrapping the output).
  4. Inspect the stored setting value
    Access the WordPress database (via phpMyAdmin or wp CLI) and query the wp_options table for options containing 'arv_lb' or look specifically for the option where the 'message' value is stored. Examine the stored value for any raw HTML or script tags.
    Affected if The stored message value in the database contains unescaped HTML or script tags that could execute in a browser.
  5. Determine if lightbox is actively loaded
    Check the plugin settings page in WordPress admin, or inspect the plugin code to see if there is a condition (such as a checkbox or setting) that controls whether the lightbox is enabled and displayed on the frontend.
    Affected if The lightbox functionality is enabled (the plugin is actively loaded and will output the vulnerable message on pages).

A user is affected if the Multi Functional Flexi Lightbox plugin is installed at version 1.2 or lower, the arv_lb[message] parameter is not sanitized before saving, the genLB() function outputs the message without escaping, and the lightbox is enabled to display on the frontend.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update the plugin to a patched version once available, or manually add `sanitize_text_field()` in the `arv_lb_options_val()` callback and apply `esc_html()` or `esc_attr()` when outputting the message in `genLB()`. Review all other settings parameters for similar sanitization issues.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
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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-2026-3347 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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