CWE-81
Improper Neutralization of Script in an Error Message Web Page
Extended description
Error pages may include customized 403 Forbidden or 404 Not Found pages. When an attacker can trigger an error that contains script syntax within the attacker's input, then cross-site scripting attacks may be possible.
Common consequences1
- ConfidentialityIntegrityAvailabilityRead Application DataExecute Unauthorized Code or Commands
Potential mitigations5
- Implementation
Do not write user-controlled input to error pages.
- Implementation
Carefully check each input parameter against a rigorous positive specification (allowlist) defining the specific characters and format allowed. All input should be neutralized, not just parameters that the user is supposed to specify, but all data in the request, including hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. We often encounter data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.
- Implementation
Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component. The problem of inconsistent output encodings often arises in web pages. If an encoding is not specified in an HTTP header, web browsers often guess about which encoding is being used. This can open up the browser to subtle XSS attacks.
- Implementation
With Struts, write all data from form beans with the bean's filter attribute set to true.
- ImplementationDefense in Depth
To help mitigate XSS attacks against the user's session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as more recent versions of Internet Explorer and Firefox), this attribute can prevent the user's session cookie from being accessible to malicious client-side scripts that use document.cookie. This is not a complete solution, since HttpOnly is not supported by all browsers. More importantly, XmlHttpRequest and other powerful browser technologies provide read access to HTTP headers, including the Set-Cookie header in which the HttpOnly flag is set.
CVEs referencing this CWE9
| CVE | Description | Severity | EPSS | Flags | Modified |
|---|---|---|---|---|---|
| CVE-2022-4137 | A reflected cross-site scripting (XSS) vulnerability was found in the 'oob' OAuth endpoint due to incorrect null-byte handling. This issue allows a malicious link to insert an arbitrary URI into a Keycloak error page. This flaw requires a user or administrator to interact with a link in order to be vulnerable. This may compromise user details, allowing it to be changed or collected by an attacker. | MEDIUM6.1 | 1.15%p63 | PoC | 2024-11-21 |
| CVE-2024-6892 | Attackers can craft a malicious link that once clicked will execute arbitrary JavaScript in the context of the Journyx web application. | MEDIUM6.1 | 0.71%p49 | 2024-11-21 | |
| CVE-2019-25027 | Missing output sanitization in default RouteNotFoundError view in com.vaadin:flow-server versions 1.0.0 through 1.0.10 (Vaadin 10.0.0 through 10.0.13), and 1.1.0 through 1.4.2 (Vaadin 11.0.0 through 13.0.5) allows attacker to execute malicious JavaScript via crafted URL | MEDIUM6.1 | 0.67%p47 | 2024-11-21 | |
| CVE-2022-4361 | Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the SAML or OIDC providers. The vulnerability can allow an attacker to execute malicious scripts by setting the AssertionConsumerServiceURL value or the redirect_uri. | MEDIUM6.1 | 0.56%p42 | PoC | 2024-11-21 |
| CVE-2024-47882 | OpenRefine is a free, open source tool for working with messy data. Prior to version 3.8.3, the built-in "Something went wrong!" error page includes the exception message and exception traceback without escaping HTML tags, enabling injection into the page if an attacker can reliably produce an error with an attacker-influenced message. It appears that the only way to reach this code in OpenRefine itself is for an attacker to somehow convince a victim to import a malicious file, which may be difficult. However, out-of-tree extensions may add their own calls to `respondWithErrorPage`. Version 3.8.3 has a fix for this issue. | MEDIUM6.1 | 0.49%p38 | 2024-10-28 | |
| CVE-2025-0883 | Improper Neutralization of Script in an Error Message Web Page vulnerability in OpenText™ Service Manager. The vulnerability could reveal sensitive information retained by the browser. This issue affects Service Manager: 9.70, 9.71, 9.72, 9.80. | NONE | 0.29%p20 | 2026-04-15 | |
| CVE-2024-47064 | Computer Vision Annotation Tool (CVAT) is an interactive video and image annotation tool for computer vision. If an attacker can trick a logged-in CVAT user into visiting a maliciously-constructed URL, they can initiate any API calls on that user's behalf. This gives the attacker temporary access to all data that the victim user has access to. Upgrade to CVAT 2.19.0 or a later version to fix this issue. | MEDIUM6.1 | 0.29%p20 | 2024-10-30 | |
| CVE-2025-24344 | A vulnerability in the error notification messages of the web application of ctrlX OS allows a remote unauthenticated attacker to inject arbitrary HTML tags and, possibly, execute arbitrary client-side code in the context of another user's browser via a crafted HTTP request. | MEDIUM6.3 | 0.28%p20 | 2026-04-15 | |
| CVE-2026-41568 | Moby is an open source container framework. In Docker Engine prior to version 29.5.1, Docker Daemon versions 28.5.2 and prior, and Moby Daemon prior to version 2.0.0-beta.14, a race condition during docker cp mount setup allows a malicious container to create empty files or directories at arbitrary absolute paths on the host filesystem. This issue has been patched in Docker Engine version 29.5.1 and Moby Daemon version 2.0.0-beta.14. | MEDIUM6.1 | 0.10%p1 | 2026-06-16 |