CWE WEAKNESSES / CWE-80
CWE-80
Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
Variant EXPLOIT LIKELIHOOD: HIGH
What it is
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.
Impact
| Confidentiality, Integrity, Availability | Read Application Data, Execute Unauthorized Code or Commands |
Mitigations
- [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 i
- [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
- [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 n
Real-world CVE examples
- CVE-2002-0938 — XSS in parameter in a link.
- CVE-2002-1495 — XSS in web-based email product via attachment filenames.
- CVE-2003-1136 — HTML injection in posted message.
- CVE-2004-2171 — XSS not quoted in error page.
Related weaknesses
Test & detect
Browse all common weaknesses, check related exploited CVEs, or map to ATT&CK techniques.
Source: MITRE CWE. View on cwe.mitre.org →