CWE Reference
CWE-177: Improper Handling of URL Encoding (Hex Encoding)
Official CWE-177 CWE context with Glexia analysis, remediation guidance, related CVEs, and ATT&CK context.
Release 4.20weaknessDraft
Glexia's Take
CWE-177: Improper Handling of URL Encoding (Hex Encoding)
Improper Handling of URL Encoding (Hex Encoding) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Integrity: Unexpected State
Developer Pattern
CWE-177 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Confidence
high confidence from CWE-177, 4.20.
Official CWE Definition
CWE-177: Improper Handling of URL Encoding (Hex Encoding)
The product does not properly handle when all or part of an input has been URL encoded.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- Missing validation
- Unsafe defaults
- Insufficient authorization or memory-safety invariant
Remediation
- Architecture and Design: Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
- Implementation: [object Object]
- Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Detection
- Code review
- SAST
- DAST
- Focused regression tests
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.