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

CVE-2026-57399

HIGH · 7.1 CVSS v3.1 Published 2026-07-13
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges 5 weeks old

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
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Proxy &amp; VPN Blocker Proxy &amp; VPN Blocker proxy-vpn-blocker allows Stored XSS.This issue affects Proxy &amp; VPN Blocker: from n/a through <= 3.5.8.

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

A stored cross-site scripting (XSS) vulnerability exists in the Proxy & VPN Blocker WordPress plugin (versions <= 3.5.8). The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing authenticated attackers to inject malicious JavaScript scripts that execute in the browsers of other users (administrators) who access the affected admin interface areas.

MitigationUpgrade to a patched version of Proxy & VPN Blocker that properly sanitizes and encodes user input before displaying it in web pages. Until a fix is available, implement WAF rules to filter malicious payloads and restrict administrative access to trusted personnel only.

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L

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. Verify Proxy & VPN Blocker plugin is installed
    Log in to WordPress admin and navigate to Plugins > Installed Plugins. Look for 'Proxy & VPN Blocker' in the list of active or installed plugins.
    Affected if The plugin is present and active in the WordPress installation.
  2. Check installed plugin version
    In the Plugins list, click on the plugin name or view details to find the version number displayed alongside the plugin name.
    Affected if The displayed version number is 3.5.8 or lower.
  3. Identify admin interface areas used by the plugin
    Navigate to the plugin settings page (usually under Settings or a dedicated menu item named 'Proxy & VPN Blocker' or similar). Review all input fields, configuration options, and areas where user-supplied data may be displayed back.
    Affected if The plugin settings page contains input fields where arbitrary text can be entered and saved.
  4. Inspect for existing XSS payloads in stored data
    Access the plugin database tables via phpMyAdmin or WP-CLI and search the options table for suspicious patterns such as '<script', 'javascript:', 'onerror=', 'onload=', or other HTML/JS tags in fields related to the plugin.
    Affected if Any records in the plugin configuration contain unsanitized HTML or JavaScript code.

A user is affected if the Proxy & VPN Blocker plugin is installed with version 3.5.8 or lower and contains any unsanitized user input stored in the database.

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

Upgrade to a patched version of Proxy & VPN Blocker that properly sanitizes and encodes user input before displaying it in web pages. Until a fix is available, implement WAF rules to filter malicious payloads and restrict administrative access to trusted personnel only.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2026-57399 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
  • No spam, self-promotion, credentials, or personal data