Weakness (CWE)
CWE-87: Improper Neutralization of Alternate XSS Syntax
The product does not neutralize or incorrectly neutralizes user-controlled input for alternate script syntax.
How to prevent it (5 mitigations)
-
Implementation
Resolve all input to absolute or canonical representations before processing.
-
Implementation
Carefully check each input parameter against a rigorous positive specification (allowlist) defining the specific characters and format allowed. All input should be neutralized, not just parameters that the user is supposed to specify, but all data in the request, including tag attributes, hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. We often encounter data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.
-
Implementation
Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
The problem of inconsistent output encodings often arises in web pages. If an encoding is not specified in an HTTP header, web browsers often guess about which encoding is being used. This can open up the browser to subtle XSS attacks.
-
Implementation
With Struts, write all data from form beans with the bean's filter attribute set to true.
-
Implementation
To help mitigate XSS attacks against the user's session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as more recent versions of Internet Explorer and Firefox), this attribute can prevent the user's session cookie from being accessible to malicious client-side scripts that use document.cookie. This is not a complete solution, since HttpOnly is not supported by all browsers. More importantly, XmlHttpRequest and other powerful browser technologies provide read access to HTTP headers, including the Set-Cookie header in which the HttpOnly flag is set.
Source: MITRE CWE-87
14 results · Clear filters · Feed
-
High 8.5
Kirby: Cross-site scripting (XSS) from incomplete HTML/XML sanitization in `Dom::sanitize()`
Kirby is an open-source content management system. Prior to 4.9.4 and 5.4.4, Kirby sites and plugins that use the writer or list fields or call Dom::sanitize(), Sane::sanitize(), Sane::Html::sanitize(), Sane::Svg::sanitize(), Sane::Xml::sanitize(), Sane::sani…
-
High 8.8
AutoGPT SignUp Page has DOM-Based XSS and Open Redirect
AutoGPT is a workflow automation platform for creating, deploying, and managing continuous artificial intelligence agents. Versions prior to 0.6.62 have a DOM-based Cross-Site Scripting (XSS) vulnerability in AutoGPT's signup page. The application improperly …
-
High 7.2
md-fileserver: Stored/Reflected XSS when viewing Markdown (raw HTML allowed)
md-fileserver allows for local viewing of markdown files in a browser. Prior to version 1.10.3, a cross-site scripting (XSS) vulnerability exists in the application’s Markdown rendering logic. When user-supplied Markdown content is rendered, embedded raw HTML…
-
High 7.4
Open WebUI: XSS via SVG in /api/v1/channels/webhooks/{webhook_id}/profile/image
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.3, the channel webhook create/update flow accepts arbitrary profile_image_url values, including data:image/svg+xml;base64,... payloads. The profile…
-
High 8.8
n8n: XSS via MCP OAuth client
n8n is an open source workflow automation platform. Prior to versions 1.123.32, 2.17.4, and 2.18.1, an unauthenticated attacker could register a malicious MCP OAuth client with a crafted client_name. If a victim user authorized the OAuth consent dialog and a …
-
High 8.1
DotNetNuke.Core has stored cross-site-scripting (XSS) via SVG upload
DNN (formerly DotNetNuke) is an open-source web content management platform (CMS) in the Microsoft ecosystem. Prior to version 10.2.2, a user could upload a specially crafted SVG file that could include scripts that can target both authenticated and unauthent…
-
High 7.6
ChurchCRM has Stored XSS in PersonView.php via Facebook Field Attribute Injection
ChurchCRM is an open-source church management system. Prior to 7.1.0, a stored cross-site scripting vulnerability exists in PersonView.php due to incorrect use of sanitizeText() as an output sanitizer for HTML attribute context. The function only strips HTML …
-
High 8.8
DOM-Based XSS in Homarr /auth/login Redirect
Homarr is an open-source dashboard. Prior to 1.57.0, a DOM-based Cross-Site Scripting (XSS) vulnerability has been discovered in Homarr's /auth/login page. The application improperly trusts a URL parameter (callbackUrl), which is passed to redirect and router…
-
High 7.1
YesWiki has Persistant Blind XSS at "/?BazaR&vue=consulter"
YesWiki is a wiki system written in PHP. Prior to version 4.6.0, a stored and blind XSS vulnerability exists in the form title field. A malicious attacker can inject JavaScript without any authentication via a form title that is saved in the backend database.…
-
High 8.8
DOM-Based XSS in Ory Polis Login Page
Ory Polis, formerly known as BoxyHQ Jackson, bridges or proxies a SAML login flow to OAuth 2.0 or OpenID Connect. Versions prior to 26.2.0 contain a DOM-based Cross-Site Scripting (XSS) vulnerability in Ory Polis's login functionality. The application imprope…
-
High 7.1
Shaarli allows reflected XSS via searchtags parameter
Shaarli is a minimalist bookmark manager and link sharing service. Prior to 0.15.0, the input string in the cloud tag page is not properly sanitized. This allows the </title> tag to be prematurely closed, leading to a reflected Cross-Site Scripting (XSS) vuln…
-
High 8.5
Hax CMS Stored Cross-Site Scripting vulnerability
HAX CMS PHP allows users to manage their microsite universe with a PHP backend. Prior to version 11.0.0, the application does not sufficiently sanitize user input, allowing for the execution of arbitrary JavaScript code. The 'saveNode' and 'saveManifest' endp…
-
High 7.1
phlex makes Cross-site Scripting (XSS) possible due to improper sanitisation of `href` attributes on `<a>` tags
phlex is an open source framework for building object-oriented views in Ruby. There is a potential cross-site scripting (XSS) vulnerability that can be exploited via maliciously crafted user data. The filter to detect and prevent the use of the `javascript:` …
-
High 7.4
JupyterLab: XSS due to lack of sanitization of the action attribute of an html <form>
JupyterLab is a user interface for Project Jupyter which will eventually replace the classic Jupyter Notebook. In affected versions untrusted notebook can execute code on load. In particular JupyterLab doesn’t sanitize the action attribute of html `<form>`. U…