CVE-2026-15098: XSS (CVSS 6.4)

Description

The Real3D Flipbook Lite plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'lightboxtext' shortcode attribute (and other unsanitized attributes handled by on_shortcode()) in versions up to, and including, 5.1.1. This is due to insufficient input sanitization and output escaping in the on_shortcode() and print_global_options() functions: shortcode attribute values are copied verbatim into $this->flipbook_options and then emitted via wp_json_encode() inside a <script type="application/json"> block without the JSON_HEX_TAG flag, allowing a literal </script> byte sequence in the attribute value to break out of the JSON script context. Because WordPress's shortcode_parse_atts() applies stripcslashes() to attribute values, an attacker can encode the breakout tag as \x3c/script\x3e\x3cscript\x3e…\x3c/script\x3e, which survives the wp_kses_post save-time filter applied to Contributor content (the escape bytes are safe text characters, not HTML tags) and is decoded to real angle brackets at render time. 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 (typically an Editor or Administrator previewing/moderating the pending post) accesses an injected page.

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CVSS v3.1 Score

6.4

MEDIUM

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

EPSS — Exploit Prediction

0.0019

Probability of exploitation

0.08%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://plugins.trac.wordpress.org/browser/real3d-flipbook-lite/tags/5.0/includes/Real3DFlipbook.php#L1224 https://plugins.trac.wordpress.org/browser/real3d-flipbook-lite/tags/5.0/includes/Real3DFlipbook.php#L1468 https://plugins.trac.wordpress.org/browser/real3d-flipbook-lite/tags/5.0/includes/Real3DFlipbook.php#L1668 https://plugins.trac.wordpress.org/changeset?reponame=&old=3643539%40real3d-flipbook-lite&new=3643539%40real3d-flipbook-lite https://www.wordfence.com/threat-intel/vulnerabilities/id/f6df3abe-ef27-46d7-bbdd-abd994fce132?source=cve

Frequently Asked Questions

What is CVE-2026-15098? +

The Real3D Flipbook Lite plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'lightboxtext' shortcode attribute (and other unsanitized attributes handled by on_shortcode()) in versions up to, and including, 5.1.1. This is due to insufficient input sanitization and output escaping in the on_shortcode() and print_global_options() functions: shortcode attribute values are copied verbatim into $this->flipbook_options and then emitted via wp_json_encode() inside a <script type="application/json"> block without the JSON_HEX_TAG flag, allowing a literal </script> byte sequence in the attribute value to break out of the JSON script context. Because WordPress's shortcode_parse_atts() applies stripcslashes() to attribute values, an attacker can encode the breakout tag as \x3c/script\x3e\x3cscript\x3e…\x3c/script\x3e, which survives the wp_kses_post save-time filter applied to Contributor content (the escape bytes are safe text characters, not HTML tags) and is decoded to real angle brackets at render time. 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 (typically an Editor or Administrator previewing/moderating the pending post) accesses an injected page. It has a CVSS v3.1 base score of 6.4 (MEDIUM).

How severe is CVE-2026-15098? +

CVE-2026-15098 has a CVSS v3.1 score of 6.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0019, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-15098? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-15098