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Weakness

Improper Neutralization of Invalid Characters in Identifiers in Web Pages

CWE-86 · Variant · Draft

The product does not neutralize or incorrectly neutralizes invalid characters or byte sequences in the middle of tag names, URI schemes, and other identifiers.

Extended description

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.

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Attack Patterns (CAPEC)

3
How adversaries exploit this weakness, per MITRE CAPEC.
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