CWE-1022: Use of Web Link to Untrusted Target with window.opener Access

VariantIncompleteExploit Likelihood: Medium

The web application produces links to untrusted external sites outside of its sphere of control, but it does not properly prevent the external site from modifying security-critical properties of the window.opener object, such as the location property.

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Extended Description

When a user clicks a link to an external site ("target"), the target="_blank" attribute causes the target site's contents to be opened in a new window or tab, which runs in the same process as the original page. The window.opener object records information about the original page that offered the link. If an attacker can run script on the target page, then they could read or modify certain properties of the window.opener object, including the location property - even if the original and target site are not the same origin. An attacker can modify the location property to automatically redirect the user to a malicious site, e.g. as part of a phishing attack. Since this redirect happens in the original window/tab - which is not necessarily visible, since the browser is focusing the display on the new target page - the user might not notice any suspicious redirection.

Technical Details

Structure: Simple
Vulnerability Mapping: ALLOWED

Applicable To

Languages

JavaScriptNot Language-Specific

Platforms

Code Examples & CVEs

Demonstrative Examples

In this example, the application opens a link in a named window/tab without taking precautions to prevent the called page from tampering with the calling page's location in the browser.

There are two ways that this weakness is commonly seen. The first is when the application generates an <a> tag is with target="_blank" to point to a target site:

BadHTML

<a href="http://attacker-site.example.com/useful-page.html" target="_blank">

In this example, the application opens a link in a named window/tab without taking precautions to prevent the called page from tampering with the calling page's location in the browser.

There are two ways that this weakness is commonly seen. The first is when the application generates an <a> tag is with target="_blank" to point to a target site:

AttackJavaScript

window.opener.location = 'http://phishing.example.org/popular-bank-page';

In this example, the application opens a link in a named window/tab without taking precautions to prevent the called page from tampering with the calling page's location in the browser.

There are two ways that this weakness is commonly seen. The first is when the application generates an <a> tag is with target="_blank" to point to a target site:

GoodHTML

<a href="http://attacker-site.example.com/useful-page.html" target="_blank" rel="noopener noreferrer">

In this example, the application opens a link in a named window/tab without taking precautions to prevent the called page from tampering with the calling page's location in the browser.

There are two ways that this weakness is commonly seen. The first is when the application generates an <a> tag is with target="_blank" to point to a target site:

BadJavaScript

var newWindow = window.open("http://attacker-site.example.com/useful-page.html", "_blank");

In this example, the application opens a link in a named window/tab without taking precautions to prevent the called page from tampering with the calling page's location in the browser.

There are two ways that this weakness is commonly seen. The first is when the application generates an <a> tag is with target="_blank" to point to a target site:

GoodJavaScript

var newWindow = window.open("http://attacker-site.example.com/useful-page.html", "_blank");newWindow.opener = null;

Observed CVE Examples (1)

Library software does not use rel: "noopener noreferrer" setting, allowing tabnabbing attacks to redirect to a malicious page

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-1022 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-1022, Use of Web Link to Untrusted Target with window.opener Access, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Prevent untrusted pages from retaining opener access

Cross-origin pages can still navigate their opener and replace a trusted page with a phishing destination. Omit the opener relationship with rel=noopener or the noopener window feature; for stronger browsing-context isolation, use Cross-Origin-Opener-Policy: same-origin.

Window: opener property — Mozilla MDN

Triage CWE-1022 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-1022, Use of Web Link to Untrusted Target with window.opener Access, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-1022

Apply MITRE's full root-cause mapping guidance when using CWE-1022, Use of Web Link to Untrusted Target with window.opener Access. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-1022 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-1022, Use of Web Link to Untrusted Target with window.opener Access. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-1022: Use of Web Link to Untrusted Target with window.opener Access?+

CWE-1022: Use of Web Link to Untrusted Target with window.opener Access is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The web application produces links to untrusted external sites outside of its sphere of control, but it does not properly prevent the external site from modifying security-critical properties of the window.opener object, such as the location property. When a user clicks a link to an external site ("target"), the target="_blank" attribute causes the target site's contents to be opened in a new window or tab, which runs in the same process as the original page. The window.opener object records information about the original page that offered the link. If an attacker can run script on the target page, then they could read or modify certain properties of the window.opener object, including the location property - even if the original and target site are not the same origin. An attacker can modify the location property to automatically redirect the user to a malicious site, e.g. as part of a phishing attack. Since this redirect happens in the original window/tab - which is not necessarily visible, since the browser is focusing the display on the new target page - the user might not notice any suspicious redirection.

What are the security consequences of Use of Web Link to Untrusted Target with window.opener Access?+

If exploited, CWE-1022 (Use of Web Link to Untrusted Target with window.opener Access) it can compromise Confidentiality, leading to outcomes such as Alter Execution Logic.

How do you prevent or mitigate Use of Web Link to Untrusted Target with window.opener Access?+

Recommended mitigations for CWE-1022 include: Specify in the design that any linked external document must not be granted access to the location object of the calling page. When creating a link to an external document using the <a> tag with a defined target, for example "_blank" or a named frame, provide the rel attribute with a value "noopener noreferrer". If opening the external document in a new window via javascript, then reset the opener by setting it equal to null. Do not use "_blank" targets. However, this can affect the usability of the application.

Which programming languages are affected by Use of Web Link to Untrusted Target with window.opener Access?+

CWE-1022 commonly affects JavaScript and Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Use of Web Link to Untrusted Target with window.opener Access?+

MITRE documents real CVEs mapped to CWE-1022, including CVE-2022-4927. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-1022 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

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