CVE-2025-61261: Angular XSS Vulnerability via CKEditor

CVE-2025-61261 Overview

CVE-2025-61261 is a reflected cross-site scripting (XSS) vulnerability affecting CKEditor 5 version 46.1.0 when integrated with Angular version 18.0.0. An attacker who convinces a user to interact with a crafted payload can execute arbitrary JavaScript in the victim's browser session. The flaw is classified under CWE-79: Improper Neutralization of Input During Web Page Generation and carries a CVSS 3.1 base score of 5.4. Successful exploitation compromises the confidentiality and integrity of the user's browser context but does not affect availability.

Critical Impact
Attackers can execute arbitrary JavaScript in the context of an authenticated user's session, enabling session token theft, DOM manipulation, and client-side account takeover.

Affected Products

CKEditor 5 version 46.1.0
Angular version 18.0.0
Web applications embedding the affected CKEditor 5 build within Angular front-ends

Discovery Timeline

2025-11-07 - CVE-2025-61261 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-61261

Vulnerability Analysis

The vulnerability is a reflected XSS flaw in the CKEditor 5 rich-text editor component when embedded in Angular applications. Reflected XSS occurs when user-controlled input is returned in an HTTP response without proper output encoding or sanitization. In this case, a crafted payload passed through the editor's input pathway reaches the DOM in an executable form. The editor renders attacker-controlled markup inside the current origin, allowing arbitrary script execution against the victim.

Exploitation requires user interaction, such as clicking a crafted link or loading a page that reflects the malicious payload back through the editor. The scope is unchanged, meaning the injected script executes within the same security context as the vulnerable application. Because CKEditor is frequently deployed in authenticated administrative and content-management workflows, the impact extends to session hijacking, credential harvesting via injected forms, and unauthorized actions performed under the victim's identity.

Root Cause

The root cause is insufficient neutralization of untrusted input rendered by CKEditor 5 46.1.0 when running inside Angular 18.0.0. HTML or script constructs supplied through the editor bypass the sanitization layer and reach the rendered DOM, violating the trust boundary between untrusted content and executable script.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker crafts a URL or input payload containing malicious markup, then delivers it to a target via phishing, malicious links, or a compromised referrer. When the victim triggers the payload within the vulnerable editor context, the browser parses and executes the attacker-controlled script under the application's origin. Refer to the Sens Cybersecurity CVE-2025-61261 Analysis for additional technical context.

Detection Methods for CVE-2025-61261

Indicators of Compromise

HTTP requests containing script fragments, event handlers (onerror, onload, onfocus), or encoded <script> tags targeting editor endpoints.
Unexpected outbound requests from browsers to attacker-controlled domains immediately after users load editor pages.
Reflected query parameters or referrer values appearing verbatim inside rendered editor content in server logs.

Detection Strategies

Inspect web application firewall (WAF) and reverse proxy logs for XSS signatures targeting CKEditor input parameters and route handlers.
Enforce and monitor a strict Content Security Policy (CSP) and log CSP violation reports for script-src and inline-script breaches.
Perform dynamic application security testing (DAST) against pages that instantiate CKEditor 5 to confirm whether crafted payloads reflect into the DOM.

Monitoring Recommendations

Alert on anomalous JavaScript errors and CSP report-uri submissions originating from editor-hosting routes.
Correlate authentication events, session token reuse, and geolocation changes shortly after users visit editor-enabled pages.
Track outbound DNS and HTTP traffic from user browsers for beacons to newly registered or low-reputation domains.

How to Mitigate CVE-2025-61261

Immediate Actions Required

Inventory applications using CKEditor 5 46.1.0 alongside Angular 18.0.0 and prioritize them for remediation.
Upgrade CKEditor 5 to the latest fixed release published by the vendor and rebuild affected Angular front-ends.
Rotate session tokens and credentials for privileged users who accessed the vulnerable editor prior to patching.

Patch Information

Upgrade CKEditor 5 to a version later than 46.1.0 that addresses the reflected XSS issue. Review the GitHub CKEditor Release v46.1.0 notes and subsequent releases for the applicable fix and integration guidance for Angular projects.

Workarounds

Deploy a strict Content Security Policy that disallows inline scripts and restricts script-src to trusted origins.
Route editor traffic through a WAF configured with rules that block XSS payloads in query strings, POST bodies, and referrer headers.
Sanitize and encode all server-side reflected values before they are passed to CKEditor, using an allowlist-based HTML sanitizer.
Restrict access to editor-enabled routes to authenticated, least-privileged users until patching is complete.

bash

# Example Content-Security-Policy header to reduce XSS impact
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'none'; report-uri /csp-report";