CVE-2026-12939

Description

The Newsletters Lite plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'link' attribute of the post_thumbnail (and newsletters_post_thumbnail) shortcodes in versions up to and including 4.15. This is due to insufficient input sanitization and output escaping in the post_thumbnail() method in helpers/shortcode.php, which concatenates the user-controlled $link shortcode attribute directly into an href attribute without esc_url() or esc_attr(). 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.

References

• https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php#L327
• https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php#L337
• https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php#L782
• https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/includes/checkinit.php#L182
• https://plugins.trac.wordpress.org/changeset?reponame=&old=3621582%40newsletters-lite&new=3621582%40newsletters-lite