CWE-939 Detail

CWE-939

Improper Authorization in Handler for Custom URL Scheme
Incomplete
2014-02-19
00h00 +00:00
2025-04-03
00h00 +00:00
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Name: Improper Authorization in Handler for Custom URL Scheme

The product uses a handler for a custom URL scheme, but it does not properly restrict which actors can invoke the handler using the scheme.

CWE Description

Mobile platforms and other architectures allow the use of custom URL schemes to facilitate communication between applications. In the case of iOS, this is the only method to do inter-application communication. The implementation is at the developer's discretion which may open security flaws in the application. An example could be potentially dangerous functionality such as modifying files through a custom URL scheme.

General Informations

Modes Of Introduction

Implementation : REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Technologies

Class: Mobile (Undetermined)

Observed Examples

References Description

CVE-2013-5725

URL scheme has action replace which requires no user prompt and allows remote attackers to perform undesired actions.

CVE-2013-5726

URL scheme has action follow and favorite which allows remote attackers to force user to perform undesired actions.

Potential Mitigations

Phases : Architecture and Design

Utilize a user prompt pop-up to authorize potentially harmful actions such as those modifying data or dealing with sensitive information.

When designing functionality of actions in the URL scheme, consider whether the action should be accessible to all mobile applications, or if an allowlist of applications to interface with is appropriate.


Vulnerability Mapping Notes

Justification : This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comment : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

References

REF-938

Scheming for Privacy and Security
Guillaume Ross.
https://brooksreview.net/2013/11/guest-post_scheming-for-privacy-and-security/

Submission

Name Organization Date Date release Version
CWE Content Team MITRE 2014-01-14 +00:00 2014-02-19 +00:00 2.6

Modifications

Name Organization Date Comment
CWE Content Team MITRE 2017-01-19 +00:00 updated Relationships
CWE Content Team MITRE 2017-11-08 +00:00 updated Modes_of_Introduction, References, Relationships
CWE Content Team MITRE 2020-02-24 +00:00 updated Applicable_Platforms, Relationships
CWE Content Team MITRE 2020-06-25 +00:00 updated Potential_Mitigations
CWE Content Team MITRE 2021-03-15 +00:00 updated Demonstrative_Examples
CWE Content Team MITRE 2023-01-31 +00:00 updated Description
CWE Content Team MITRE 2023-04-27 +00:00 updated References, Relationships
CWE Content Team MITRE 2023-06-29 +00:00 updated Mapping_Notes
CWE Content Team MITRE 2025-04-03 +00:00 updated Demonstrative_Examples