CVE-2026-15298 Overview
CVE-2026-15298 is a DOM-Based Cross-Site Scripting (XSS) vulnerability affecting the TelSender plugin for WordPress in all versions up to and including 1.14.14. The flaw stems from insufficient input sanitization when the plugin processes Telegram API responses containing attacker-controlled chat titles. An unauthenticated attacker can inject malicious scripts through a Telegram chat title. The payload executes when a WordPress administrator opens the TelSender settings page and clicks the Tested button. The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation).
Critical Impact
Unauthenticated attackers can execute arbitrary JavaScript in an administrator's browser session, potentially leading to session theft, plugin configuration tampering, and further WordPress site compromise.
Affected Products
- TelSender plugin for WordPress — all versions up to and including 1.14.14
- WordPress installations using the vulnerable TelSender plugin build (tags/1.14.14)
- WordPress installations running the vulnerable TelSender trunk build prior to the fix
Discovery Timeline
- 2026-07-10 - CVE-2026-15298 published to NVD
- 2026-07-10 - Last updated in NVD database
Technical Details for CVE-2026-15298
Vulnerability Analysis
The TelSender plugin integrates WordPress with the Telegram Bot API. When an administrator triggers a connectivity test, client-side JavaScript in js/ajax.js fetches Telegram API responses and writes chat metadata into the DOM without sanitization. Because chat titles are attacker-controlled, an adversary can create a Telegram chat whose title contains a JavaScript payload and cause the WordPress site's bot to be added to it. When the administrator clicks the Tested button on the settings page, the malicious title is rendered into the DOM and the script executes in the administrator's authenticated session.
Root Cause
The root cause is missing output encoding in the client-side rendering path. The vulnerable code at js/ajax.js#L119 and js/ajax.js#L139 inserts Telegram API response fields directly into HTML sinks such as innerHTML. The server-side template at template/view.php#L111 also relies on unsanitized data. Because the Telegram API returns arbitrary user-supplied content, any chat title becomes an injection vector.
Attack Vector
Exploitation is unauthenticated and network-based. An attacker creates a Telegram chat with a payload embedded in the title, then invites the site's configured bot. When an administrator visits the TelSender settings page and clicks Tested, the plugin queries the Telegram API, receives the malicious title, and injects it into the settings view. The payload executes with the administrator's privileges and can create new admin users, modify plugin options, or exfiltrate session cookies.
No verified proof-of-concept code has been published. See the Wordfence Vulnerability Report and the WordPress TelSender AJAX Script for the vulnerable code paths.
Detection Methods for CVE-2026-15298
Indicators of Compromise
- Unexpected WordPress administrator accounts created shortly after an admin visited the TelSender settings page.
- Outbound requests from an administrator's browser to unfamiliar domains immediately following clicks on the Tested button.
- Modifications to WordPress wp_options entries related to the TelSender plugin without a corresponding admin change log entry.
- Telegram bot membership in chats with unusual or script-like chat titles containing characters such as <, >, or script.
Detection Strategies
- Inventory WordPress sites and identify installations of the TelSender plugin at version 1.14.14 or earlier.
- Inspect browser network logs from administrator sessions for anomalous script loads sourced from the admin.php?page=telsender context.
- Review the js/ajax.js file against the fixed upstream version to confirm sanitization is in place.
Monitoring Recommendations
- Enable WordPress audit logging for administrator actions, user creation, and plugin configuration changes.
- Monitor web server access logs for administrator requests to TelSender AJAX endpoints followed by unusual outbound activity.
- Alert on new administrator role assignments or REST API key generation in WordPress.
How to Mitigate CVE-2026-15298
Immediate Actions Required
- Update the TelSender plugin to a version later than 1.14.14 once a patched release is available from the plugin author.
- Deactivate the TelSender plugin on all WordPress sites until a patched version is confirmed installed.
- Rotate all WordPress administrator credentials and Telegram bot API tokens if the settings page was accessed while the plugin was vulnerable.
Patch Information
A fix has been committed upstream. Review the WordPress TelSender Changeset and the Wordfence Vulnerability Report for the corrected code and confirmed fixed version. Apply the update through the WordPress plugin manager and verify the installed version reflects the patched release.
Workarounds
- Restrict administrator access to the TelSender settings page using role-based access controls or plugins that limit wp-admin sections by role.
- Configure a Web Application Firewall rule to strip or block HTML metacharacters in Telegram API response bodies rendered by the plugin.
- Remove the configured Telegram bot from any chats not owned by trusted operators to reduce exposure to attacker-controlled chat titles.
# Configuration example: quickly disable the vulnerable plugin via WP-CLI
wp plugin deactivate telsender --all
wp plugin status telsender
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
