{"id":"CVE-2026-118166","kind":"vulnerability","aliases":["CVE-2026-118166"],"related":[],"title":"WordPress Mailchimp plugin: unauthenticated visitors can run registered shortcodes","description":"The MC4WP: Mailchimp for WordPress WordPress plugin before 4.15.0 does not prevent request-derived values in its dynamic content tags from being processed as shortcodes when a form is embedded with its block, allowing unauthenticated visitors to execute arbitrary registered shortcodes with attacker-chosen attributes. This requires the site owner to have added a request-derived tag to the form content and to embed the form with the block rather than the classic shortcode.","summary":"The MC4WP Mailchimp for WordPress plugin before 4.15.0 lets request-derived values in dynamic content tags be processed as shortcodes when a form is embedded with its block. An unauthenticated visitor can execute any registered shortcode with attacker-chosen attributes.","severity":"medium","cvss":4.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["mailchimp-for-wordpress","mc4wp","package","wordpress"],"not_affected_if":["classic-shortcode-only","no-request-derived-tags","version-4.15.0-or-later"],"how_to_check":"- Check the installed version of the MC4WP: Mailchimp for WordPress plugin in the WordPress admin plugins list; it is affected below `4.15.0`.\n- Look for a request-derived dynamic content tag (such as a URL or query parameter tag) in forms that are embedded with the MC4WP block.","fix":"- MC4WP: Mailchimp for WordPress: upgrade to `4.15.0` or later.","status":"open","published_at":"2026-11-06T08:17:18+00:00","first_seen_at":"2026-11-06T08:40:32+00:00","triaged_at":"2026-11-06T08:42:43+00:00","updated_at":"2026-11-06T08:42:43+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-11-06T08:42:43Z","model":"claude-haiku-5-5","output":{"fix":"- MC4WP: Mailchimp for WordPress: upgrade to `4.15.0` or later.","reach":"internet","title":"WordPress Mailchimp plugin: unauthenticated visitors can run registered shortcodes","impact":"medium","summary":"The MC4WP Mailchimp for WordPress plugin before 4.15.0 lets request-derived values in dynamic content tags be processed as shortcodes when a form is embedded with its block. An unauthenticated visitor can execute any registered shortcode with attacker-chosen attributes.","audience":"businesses","category":"package","nicknames":[],"who_cares":["wordpress","mc4wp","mailchimp-for-wordpress"],"confidence":0.7,"fix_status":"available","needs_auth":"no","worst_case":"unauthenticated visitors run any registered shortcode with chosen attributes","analyst_note":"","how_to_check":"- Check the installed version of the MC4WP: Mailchimp for WordPress plugin in the WordPress admin plugins list; it is affected below `4.15.0`.\n- Look for a request-derived dynamic content tag (such as a URL or query parameter tag) in forms that are embedded with the MC4WP block.","plain_action":"","needs_analyst":false,"not_affected_if":["version-4.15.0-or-later","classic-shortcode-only","no-request-derived-tags"],"who_is_affected":"Sites running the MC4WP: Mailchimp for WordPress plugin before 4.15.0 where the site owner added a request-derived dynamic content tag to a form and embedded that form with the block rather than the classic shortcode. Sites that use only the classic shortcode, or forms without request-derived tags, are not described as exposed.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000745,"input_tokens":4287,"output_tokens":632,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-118166':12A,15A '-2026':11A,14A '4.15.0':30B,73C 'add':119C 'allow':99C 'arbitrari':104C 'attack':62B,109C 'attacker-chosen':61B,108C 'attribut':64B,111C 'block':51B,98C,136C 'chosen':63B,110C 'classic':140C 'content':38B,84C,128C 'cve':10A,13A 'deriv':34B,79C,123C 'dynam':37B,83C 'emb':131C 'embed':48B,95C 'execut':56B,103C 'form':46B,93C,127C,133C 'let':31B 'mailchimp':2A,17B,25B,67C 'mailchimp-for-wordpress':16B 'mc4wp':20B,24B,66C 'owner':116C 'packag':21B 'plugin':3A,28B,71C 'prevent':76C 'process':41B,88C 'rather':137C 'regist':8A,58B,105C 'request':33B,78C,122C 'request-deriv':32B,77C,121C 'requir':113C 'run':7A 'shortcod':9A,43B,59B,90C,106C,141C 'site':115C 'tag':39B,85C,124C 'unauthent':4A,53B,100C 'valu':35B,80C 'visitor':5A,54B,101C 'wordpress':1A,19B,22B,27B,69C,70C","nicknames":[],"mitigations":[],"who_affected":"Sites running the MC4WP: Mailchimp for WordPress plugin before 4.15.0 where the site owner added a request-derived dynamic content tag to a form and embedded that form with the block rather than the classic shortcode. Sites that use only the classic shortcode, or forms without request-derived tags, are not described as exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["mailchimpforwordpress","mc4wp","medium","package","wordpress"],"campaign_type":null,"search_a":"'-118166':12A,15A '-2026':11A,14A 'cve':10A,13A 'mailchimp':2A 'plugin':3A 'regist':8A 'run':7A 'shortcod':9A 'unauthent':4A 'visitor':5A 'wordpress':1A","search_b":"'4.15.0':30B 'attack':62B 'attacker-chosen':61B 'attribut':64B 'block':51B 'chosen':63B 'content':38B 'deriv':34B 'dynam':37B 'embed':48B 'execut':56B 'form':46B 'let':31B 'mailchimp':17B,25B 'mailchimp-for-wordpress':16B 'mc4wp':20B,24B 'packag':21B 'plugin':28B 'process':41B 'regist':58B 'request':33B 'request-deriv':32B 'shortcod':43B,59B 'tag':39B 'unauthent':53B 'valu':35B 'visitor':54B 'wordpress':19B,22B,27B","search_c":"'4.15.0':73C 'add':119C 'allow':99C 'arbitrari':104C 'attack':109C 'attacker-chosen':108C 'attribut':111C 'block':98C,136C 'chosen':110C 'classic':140C 'content':84C,128C 'deriv':79C,123C 'dynam':83C 'emb':131C 'embed':95C 'execut':103C 'form':93C,127C,133C 'mailchimp':67C 'mc4wp':66C 'owner':116C 'plugin':71C 'prevent':76C 'process':88C 'rather':137C 'regist':105C 'request':78C,122C 'request-deriv':77C,121C 'requir':113C 'shortcod':90C,106C,141C 'site':115C 'tag':85C,124C 'unauthent':100C 'valu':80C 'visitor':101C 'wordpress':69C,70C","first_public_at":"2026-11-06T08:17:18+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","cvss_by":"contact@wpscan.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-118166","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118166","severity":null,"published_at":"2026-11-06T08:17:18+00:00","modified_at":"2026-11-06T08:17:18+00:00","first_seen_at":"2026-11-06T08:40:32+00:00","fetched_at":"2026-11-06T08:40:32+00:00","note":null}],"documents":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}