CWE - CWE-1021: Improper Restriction of Rendered UI Layers or Frames (4.20)
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    CWE-1021: Improper Restriction of Rendered UI Layers or Frames

    Weakness ID: 1021
    Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
    Abstraction: Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
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    + Description
    The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain. Diagram for CWE-1021
    + Alternate Terms
    Clickjacking
    UI Redress Attack
    Tapjacking
    "Tapjacking" is similar to clickjacking, except it is used for mobile applications in which the user "taps" the application instead of performing a mouse click.
    + Common Consequences
    Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
    Impact Details

    Gain Privileges or Assume Identity; Bypass Protection Mechanism; Read Application Data; Modify Application Data

    		Scope: Access Control

    An attacker can trick a user into performing actions that are masked and hidden from the user's view. The impact varies widely, depending on the functionality of the underlying application. For example, in a social media application, clickjacking could be used to trick the user into changing privacy settings.
    + Potential Mitigations
    Phase(s) Mitigation

    Implementation

    The use of X-Frame-Options allows developers of web content to restrict the usage of their application within the form of overlays, frames, or iFrames. The developer can indicate from which domains can frame the content.

    The concept of X-Frame-Options is well documented, but implementation of this protection mechanism is in development to cover gaps. There is a need for allowing frames from multiple domains.

    Implementation

    A developer can use a "frame-breaker" script in each page that should not be framed. This is very helpful for legacy browsers that do not support X-Frame-Options security feature previously mentioned.

    It is also important to note that this tactic has been circumvented or bypassed. Improper usage of frames can persist in the web application through nested frames. The "frame-breaking" script does not intuitively account for multiple nested frames that can be presented to the user.

    Implementation
    This defense-in-depth technique can be used to prevent the improper usage of frames in web applications. It prioritizes the valid sources of data to be loaded into the application through the usage of declarative policies. Based on which implementation of Content Security Policy is in use, the developer should use the "frame-ancestors" directive or the "frame-src" directive to mitigate this weakness. Both directives allow for the placement of restrictions when it comes to allowing embedded content.

    Implementation
    In addition to frames or iframes as previously mentioned, the web application is expected to place restrictions on whether it is allowed to be rendered within objects, embed, or applet elements.
    + Relationships
    Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
    + Relevant to the view "Research Concepts" (View-1000)
    Nature Type ID Name
    ChildOf Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 441 Unintended Proxy or Intermediary ('Confused Deputy')
    ChildOf Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 451 User Interface (UI) Misrepresentation of Critical Information
    + Relevant to the view "Software Development" (View-699)
    Nature Type ID Name
    MemberOf Category Category - a CWE entry that contains a set of other entries that share a common characteristic. 355 User Interface Security Issues
    + Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)
    Nature Type ID Name
    ChildOf Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 610 Externally Controlled Reference to a Resource in Another Sphere
    + Modes Of Introduction
    Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
    Phase Note
    Implementation
    + Applicable Platforms
    Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.
    Languages

    Class: Not Language-Specific (Undetermined Prevalence)

    Technologies

    Class: Not Technology-Specific (Undetermined Prevalence)

    Class: Web Based (Undetermined Prevalence)

    + Selected Observed Examples

    Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

    Reference Description
    E-mail preview feature in a desktop application allows clickjacking attacks via a crafted e-mail message
    Hardware/firmware product has insufficient clickjacking protection in its web user interface
    Clickjacking in data-loss prevention product via HTTP response header.
    Tapjacking in permission dialog for mobile OS allows access of private storage using a partially-overlapping window.
    Tapjacking in web browser related to page navigation and touch/gesture events.
    System UI in mobile OS allows a malicious application to create a UI overlay of the entire screen to gain privileges.
    + Weakness Ordinalities
    Ordinality Description
    Primary
    (where the weakness exists independent of other weaknesses)
    + Detection Methods
    Method Details

    Automated Static Analysis
    Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

    Effectiveness: High
    + Memberships
    Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
    Nature Type ID Name
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1348 OWASP Top Ten 2021 Category A04:2021 - Insecure Design
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1396 Comprehensive Categorization: Access Control
    MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1441 OWASP Top Ten 2025 Category A06:2025 - Insecure Design
    + Vulnerability Mapping Notes
    Usage ALLOWED
    (this CWE ID may be used to map to real-world vulnerabilities)
    Reason Acceptable-Use

    Rationale

    		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.

    Comments

    		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-1491] Wikipedia. "Clickjacking". 2025-11-10.
    <https://en.wikipedia.org/wiki/Clickjacking>. (URL validated: 2025-11-10)
    [REF-36] OWASP. "Clickjacking - OWASP".
    <https://owasp.org/www-community/attacks/Clickjacking>. (URL validated: 2023-04-07)
    [REF-35] Andrew Horton. "Clickjacking For Shells".
    <https://www.exploit-db.com/docs/17881.pdf>.
    [REF-37] Internet Security. "SecTheory".
    <https://www.sectheory.com/clickjacking.htm>. (URL validated: 2023-04-07)
    [REF-38] W3C. "Content Security Policy Level 3".
    <https://w3c.github.io/webappsec-csp/>.
    + Content History
    + Submissions
    Submission Date Submitter Organization
    2017-08-01
    (CWE 2.12, 2017-11-08)     		CWE Content Team MITRE
    + Modifications
    Modification Date Modifier Organization
    2026-04-30
    (CWE 4.20, 2026-04-30)     		CWE Content Team MITRE
    updated Common_Consequences, Description, Diagram, Potential_Mitigations
    2025-12-11
    (CWE 4.19, 2025-12-11)     		CWE Content Team MITRE
    updated Applicable_Platforms, References, Relationships, Weakness_Ordinalities
    2023-06-29
    (CWE 4.12, 2023-06-29)     		CWE Content Team MITRE
    updated Mapping_Notes
    2023-04-27
    (CWE 4.11, 2023-04-27)     		CWE Content Team MITRE
    updated Detection_Factors, References, Relationships
    2023-01-31
    (CWE 4.10, 2023-01-31)     		CWE Content Team MITRE
    updated Related_Attack_Patterns
    2021-10-28
    (CWE 4.6, 2021-10-28)     		CWE Content Team MITRE
    updated Relationships
    2020-08-20
    (CWE 4.2, 2020-08-20)     		CWE Content Team MITRE
    updated Related_Attack_Patterns
    2020-06-25
    (CWE 4.1, 2020-06-25)     		CWE Content Team MITRE
    updated Potential_Mitigations
    2020-02-24
    (CWE 4.0, 2020-02-24)     		CWE Content Team MITRE
    updated Applicable_Platforms, Relationships
    2019-06-20
    (CWE 3.3, 2019-06-20)     		CWE Content Team MITRE
    updated Related_Attack_Patterns, Relationships
    Page Last Updated: April 30, 2026