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

CVE-2026-1854

MEDIUM · 6.4 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 →
70/100
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 Post Flagger plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'flag' shortcode in all versions up to, and including, 1.1 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

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 · moderate confidence

The Post Flagger WordPress plugin is vulnerable to stored XSS via the 'flag' shortcode due to insufficient input sanitization and output escaping on user-supplied attributes. Authenticated users with contributor-level access or higher can inject arbitrary JavaScript that executes when pages containing the shortcode are accessed.

MitigationUpdate to a patched version of the plugin when available. Until then, review the shortcode handler code to add proper input sanitization (e.g., sanitize_text_field) and output escaping (e.g., esc_attr, esc_html) for all user-supplied attributes.

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
Low
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/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 Post Flagger plugin installation and version
    In WordPress admin, go to Plugins > Installed Plugins and locate Post Flagger. Note the version number displayed. Compare against any known affected version range for this plugin.
    Affected if The plugin is installed and its version falls within the affected range (if a patched version exists, any version prior to that is potentially affected).
  2. Identify shortcode usage in content
    Search your WordPress database for instances of the [flag] shortcode in posts, pages, or custom post types. Use phpMyAdmin or WP-CLI: wpdb->get_results("SELECT ID, post_title FROM wp_posts WHERE post_content LIKE '%[flag%' AND post_status = 'publish'").
    Affected if The shortcode is present in any published content, as this provides the injection vector.
  3. Examine shortcode handler code for sanitization gaps
    Access the plugin files via FTP or file manager. Locate the shortcode handler function (typically in the main plugin file or a shortcodes.php file). Inspect all attributes used within the handler for use of sanitization functions like sanitize_text_field, esc_attr, or esc_html.
    Affected if Any user-supplied shortcode attribute lacks proper input sanitization (sanitize_text_field) AND output escaping (esc_attr or esc_html), allowing script injection.
  4. Audit user roles with shortcode access
    In WordPress admin, go to Users and review which roles have contributor-level or higher access. Check if any such users exist on the site.
    Affected if At least one user with contributor-level or higher permission exists, as they can create or edit content containing the malicious shortcode.

You are affected if the Post Flagger plugin is installed, the [flag] shortcode is used in published content, and the shortcode handler lacks proper input sanitization and output escaping on its attributes, combined with at least one contributor-level user present on the site.

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 to a patched version of the plugin when available. Until then, review the shortcode handler code to add proper input sanitization (e.g., sanitize_text_field) and output escaping (e.g., esc_attr, esc_html) for all user-supplied attributes.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

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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-2026-1854 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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