CVE-2026-109972: s2Member <= 261011 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'date_format' Shortcode Attribute

Severity: medium (CVSS 6.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-28 · updated 2026-10-28
Weakness: CWE-79

Description

The s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'date_format' parameter in all versions up to, and including, <= 261011 due to insufficient input sanitization and output escaping. 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. The payload bypasses wp_kses_post() on save because it contains no literal angle brackets — only backslash-escaped sequences that PHP's date() materializes into HTML tag characters at render time after WordPress's shortcode_parse_atts() applies stripcslashes() to the attribute value.

Affected products

clavaque s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions: through 261011

References

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