VariantDraft

CWE-86Improper Neutralization of Invalid Characters in Identifiers in Web Pages

Category: other

Description

The product does not neutralize or incorrectly neutralizes invalid characters or byte sequences in the middle of tag names, URI schemes, and other identifiers. Some web browsers may remove these sequences, resulting in output that may have unintended control implications. For example, the product may attempt to remove a "javascript:" URI scheme, but a "java%00script:" URI may bypass this check and still be rendered as active javascript by some browsers, allowing XSS or other attacks.

Common consequences· 1

  • Confidentiality / Integrity / Availability — Read Application Data, Execute Unauthorized Code or Commands

Potential mitigations· 2

  • [Implementation]
  • [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.

Related CAPEC attack patterns· 3

CAPEC-247CAPEC-73CAPEC-85

References

  1. https://cwe.mitre.org/data/definitions/86.html

Exploits (incoming)3

TypeTargetConfidenceTier
AttackPatternUser-Controlled Filenamecapec-73100%live
AttackPatternAJAX Footprintingcapec-85100%live
AttackPatternXSS Using Invalid Characterscapec-247100%live

(incoming)1

TypeTargetConfidenceTier
VulnerabilityCVE-2025-66606cve-2025-666060%live

Related by meaning· 6

Nearest entities by semantic similarity across the cs-graph corpus.

CWE
Improper Neutralization of Alternate XSS Syntax
CWE
Improper Neutralization of Script in an Error Message Web Page
CWE
Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
CWE
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE
Improper Neutralization of HTTP Headers for Scripting Syntax
CWE
Improper Neutralization of Script in Attributes in a Web Page
Sourced from MITRE CWE 4.20. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.