{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-42235/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[],"_cs_exploited":false,"_cs_products":["n8n"],"_cs_severities":["high"],"_cs_tags":["xss","oauth","n8n","CVE-2026-42235"],"_cs_type":"advisory","_cs_vendors":["npm"],"content_html":"\u003cp\u003en8n, a workflow automation platform, is susceptible to a cross-site scripting (XSS) vulnerability (CVE-2026-42235) related to the registration of malicious MCP OAuth clients. An unauthenticated attacker can register an OAuth client with a crafted \u003ccode\u003eclient_name\u003c/code\u003e containing malicious JavaScript. This vulnerability exists in versions prior to 2.14.2 and also affects versions 2.17.0 to 2.17.3 and 2.18.0. A successful exploit allows the attacker to execute arbitrary JavaScript within a victim\u0026rsquo;s authenticated n8n session, potentially leading to credential theft, session token theft, workflow manipulation, or privilege escalation. Defenders should prioritize patching to version 2.14.2 or later to mitigate the risk.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn unauthenticated attacker registers a malicious MCP OAuth client with a crafted \u003ccode\u003eclient_name\u003c/code\u003e containing XSS payload.\u003c/li\u003e\n\u003cli\u003eA victim user navigates to the n8n instance and is presented with the malicious OAuth consent dialog.\u003c/li\u003e\n\u003cli\u003eThe victim user authorizes the malicious OAuth client, unknowingly injecting the attacker\u0026rsquo;s script into their session.\u003c/li\u003e\n\u003cli\u003eA second user, possibly an administrator, revokes the OAuth access granted to the malicious client.\u003c/li\u003e\n\u003cli\u003eThis revocation triggers a toast notification to the original victim user.\u003c/li\u003e\n\u003cli\u003eThe toast notification renders the attacker\u0026rsquo;s injected script from the crafted \u003ccode\u003eclient_name\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe victim user clicks on the link within the toast notification.\u003c/li\u003e\n\u003cli\u003eThe injected JavaScript executes within the victim\u0026rsquo;s authenticated n8n browser session, enabling the attacker to perform malicious actions such as stealing credentials, manipulating workflows, or escalating privileges.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of this XSS vulnerability can lead to significant compromise of an n8n instance. Attackers can steal user credentials and session tokens, allowing them to impersonate legitimate users. Malicious actors could also modify or create workflows, leading to data breaches, system disruption, or unauthorized access. Privilege escalation is also possible, potentially granting attackers administrative control over the n8n platform. The number of potential victims depends on the exposure and user base of the vulnerable n8n instances.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade n8n to version 2.14.2 or later to patch CVE-2026-42235, as recommended in the advisory.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eDetect Suspicious n8n MCP OAuth Client Registration\u003c/code\u003e to identify attempts to register OAuth clients with suspicious names.\u003c/li\u003e\n\u003cli\u003eIf immediate patching is not feasible, restrict access to the n8n instance and the MCP OAuth registration endpoint to trusted users only, as suggested in the advisory\u0026rsquo;s workaround.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-04-29T21:25:44Z","date_published":"2026-04-29T21:25:44Z","id":"/briefs/2026-05-n8n-xss-oauth/","summary":"n8n is vulnerable to cross-site scripting (XSS) via a malicious MCP OAuth client, allowing an unauthenticated attacker to inject arbitrary JavaScript into an authenticated user's session.","title":"n8n MCP OAuth Client XSS Vulnerability","url":"https://feed.craftedsignal.io/briefs/2026-05-n8n-xss-oauth/"}],"language":"en","title":"CraftedSignal Threat Feed — CVE-2026-42235","version":"https://jsonfeed.org/version/1.1"}