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Weakness (CWE)

CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page

Variant Incomplete

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.

How to prevent it (4 mitigations)
  1. 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 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.

  2. 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.

  3. Implementation

    With Struts, write all data from form beans with the bean's filter attribute set to true.

  4. 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-80

691 results · Feed

  • Medium 5.4

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  • Low 1.8

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  • High 7.8

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  • High 8.1

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  • Medium 6.3

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  • Medium 6.1

    MapServer: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) in OpenLayers viewer

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  • Low 3.1

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  • Medium 4.8

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  • Critical 9.3

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  • Medium 5.3

    Zammad improperly neutralizes of script-related HTML tags in ticket articles

    Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.1 and 6.5.4, the HTML sanitizer for ticket articles was missing proper sanitization of data: ... URI schemes, resulting in storing such malicious content in the database of the Z…

  • Medium 5.3

    WordPress tagDiv Composer plugin <= 5.4.3 - Arbitrary Shortcode Execution vulnerability

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  • Medium 5.3

    WordPress Uminex theme <= 1.0.9 - Arbitrary Shortcode Execution vulnerability

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  • Medium 5.3

    WordPress Armania theme <= 1.4.8 - Arbitrary Shortcode Execution vulnerability

    Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability in kutethemes Armania armania allows Code Injection.This issue affects Armania: from n/a through <= 1.4.8.

  • Medium 5.3

    WordPress TechOne theme <= 3.0.3 - Arbitrary Shortcode Execution vulnerability

    Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability in kutethemes TechOne techone allows Code Injection.This issue affects TechOne: from n/a through <= 3.0.3.

  • Medium 5.3

    WordPress DukaMarket theme <= 1.3.0 - Arbitrary Shortcode Execution vulnerability

    Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability in kutethemes DukaMarket dukamarket allows Code Injection.This issue affects DukaMarket: from n/a through <= 1.3.0.

  • Medium 6.3

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    Improper neutralization of Script-Related HTML tags in a web page (basic XSS) vulnerability in WikiWorks Mediawiki - Cargo Extension allows Stored XSS.This issue affects Mediawiki - Cargo Extension: before 3.8.7.