CVE-2026-111109

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    CVE-2026-111109

    Published: 31 Oct 2026Last Modified: 4 Nov 2026

    Summary: Webmention <= 5.10.1 - Unauthenticated Stored Cross-Site Scripting via Open Graph og:title Meta Tag

    Details: The Webmention plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Open Graph og:title meta tag of a webmention source URL in versions up to, and including, 5.10.1. This is due to insufficient input sanitization: Meta::add_properties() maps og:title to the Item::name property, but Item has no concrete set_name() method, so Item::__call() stores the value raw while sibling set_content()/set_summary() paths route through webmention_sanitize_html(); Item::get_content() then falls back to the raw name when content and summary are empty, and Receiver::process() explicitly removes the core wp_filter_kses / wp_filter_post_kses hooks on pre_comment_content before calling wp_new_comment(), so the payload is persisted to comment_content as-is. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page, after an administrator approves the resulting pending webmention comment. Successful exploitation additionally requires an action by an administrator — the attacker cannot trigger the vulnerability on their own.

    References: https://plugins.trac.wordpress.org/browser/webmention/tags/5.10.1/includes/class-receiver.php#L267, https://plugins.trac.wordpress.org/browser/webmention/tags/5.10.1/includes/class-receiver.php#L453, https://plugins.trac.wordpress.org/browser/webmention/tags/5.10.1/includes/entity/class-item.php#L125, https://plugins.trac.wordpress.org/browser/webmention/tags/5.10.1/includes/entity/class-item.php#L297, https://plugins.trac.wordpress.org/browser/webmention/tags/5.10.1/includes/handler/class-meta.php#L78, https://plugins.trac.wordpress.org/browser/webmention/tags/5.10.2/includes/class-receiver.php, https://www.wordfence.com/threat-intel/vulnerabilities/id/0b283d17-b89f-467d-8a79-cdf7b9bfdb65?source=cve, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/111xxx/CVE-2026-111109.json, https://nvd.nist.gov/vuln/detail/CVE-2026-111109, https://github.com/pfefferle/wordpress-webmention/pull/698

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    5.10.1
    5.10.0

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2026-111109 | CVE-DB