CWE-79
AllowedImproper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Abstraction: Base · Status: Stable
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
66688 vulnerabilities reference this CWE, most recent first.
GHSA-2FVG-6M83-PJW6
Vulnerability from github – Published: 2022-08-13 00:00 – Updated: 2022-08-16 00:00A cross-site scripting (XSS) vulnerability in Rule Engine in ThingsBoard 3.3.1 allows remote attackers (with administrative access) to inject arbitrary JavaScript within the title of a rule node.
{
"affected": [],
"aliases": [
"CVE-2021-42750"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-08-12T17:15:00Z",
"severity": "MODERATE"
},
"details": "A cross-site scripting (XSS) vulnerability in Rule Engine in ThingsBoard 3.3.1 allows remote attackers (with administrative access) to inject arbitrary JavaScript within the title of a rule node.",
"id": "GHSA-2fvg-6m83-pjw6",
"modified": "2022-08-16T00:00:24Z",
"published": "2022-08-13T00:00:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-42750"
},
{
"type": "WEB",
"url": "https://github.com/thingsboard/thingsboard"
},
{
"type": "WEB",
"url": "https://packetstormsecurity.com/files/167999/Thingsboard-3.3.1-Cross-Site-Scripting.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2FVG-VJRP-6XV7
Vulnerability from github – Published: 2022-02-11 00:00 – Updated: 2026-07-05 03:30A reflected cross-site-scripting attack in web application of D-Link DIR-X1860 before v1.10WWB09_Beta allows a remote unauthenticated attacker to execute code in the device of the victim via sending a specific URL to the unauthenticated victim.
{
"affected": [],
"aliases": [
"CVE-2021-41445"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-02-10T17:15:00Z",
"severity": "MODERATE"
},
"details": "A reflected cross-site-scripting attack in web application of D-Link DIR-X1860 before v1.10WWB09_Beta allows a remote unauthenticated attacker to execute code in the device of the victim via sending a specific URL to the unauthenticated victim.",
"id": "GHSA-2fvg-vjrp-6xv7",
"modified": "2026-07-05T03:30:44Z",
"published": "2022-02-11T00:00:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-41445"
},
{
"type": "WEB",
"url": "https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10283"
},
{
"type": "WEB",
"url": "https://www.dlink.com/en/security-bulletin"
},
{
"type": "WEB",
"url": "http://d-link.com"
},
{
"type": "WEB",
"url": "http://dir-x1860.com"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2FVV-QXRQ-7JQ6
Vulnerability from github – Published: 2022-08-18 18:55 – Updated: 2022-08-18 18:55Impact
The default landing page contained HTML to display a sample curl command which is made visible if the full landing page bundle could not be fetched from Apollo's CDN. The server's URL is directly interpolated into this command inside the browser from window.location.href. On some older browsers such as IE11, this value is not URI-encoded. On such browsers, opening a malicious URL pointing at an Apollo Router could cause execution of attacker-controlled JavaScript.
This only affects Apollo Server with the default landing page enabled. Old browsers visiting your server may be affected if ANY of these apply:
- You do not pass any landing page plugin to the plugins option of new ApolloServer.
- You pass ApolloServerPluginLandingPageLocalDefault() or ApolloServerPluginLandingPageProductionDefault() to the plugins option of new ApolloServer.
Browsers visiting your server are NOT affected if ANY of these apply:
- You pass ApolloServerPluginLandingPageDisabled() to the plugins option of new ApolloServer.
- You pass ApolloServerPluginLandingPageGraphQLPlayground() to the plugins option of new ApolloServer.
- You pass a custom plugin implementing the renderLandingPage hook to the plugins option of new ApolloServer.
This issue was introduced in v3.0.0 when the landing page feature was added.
Patches
To avoid this, the sample curl command has been removed in release 3.10.1.
Workarounds
Disabling the landing page removes the possibility of exploit:
import { ApolloServerPluginLandingPageDisabled } from 'apollo-server-core';
new ApolloServer({
plugins: [ApolloServerPluginLandingPageDisabled()],
// ...
});
See also
A similar issue exists in the landing page of Apollo Router. See the corresponding Apollo Router security advisory.
For more information
If you have any questions or comments about this advisory: * Open an issue in the Apollo Server repository * Email us at security@apollographql.com
Credits
This issue was discovered by Adrian Denkiewicz of Doyensec.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "apollo-server-core"
},
"ranges": [
{
"events": [
{
"introduced": "3.0.0"
},
{
"fixed": "3.10.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2022-08-18T18:55:01Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "### Impact\n\nThe default landing page contained HTML to display a sample `curl` command which is made visible if the full landing page bundle could not be fetched from Apollo\u0027s CDN. The server\u0027s URL is directly interpolated into this command inside the browser from `window.location.href`. On some older browsers such as IE11, this value is not URI-encoded. On such browsers, opening a malicious URL pointing at an Apollo Router could cause execution of attacker-controlled JavaScript.\n\nThis only affects Apollo Server with the [default landing page](https://www.apollographql.com/docs/apollo-server/api/plugin/landing-pages/) enabled. Old browsers visiting your server may be affected if ANY of these apply:\n- You do not pass any landing page plugin to the `plugins` option of `new ApolloServer`.\n- You pass `ApolloServerPluginLandingPageLocalDefault()` or `ApolloServerPluginLandingPageProductionDefault()` to the `plugins` option of `new ApolloServer`.\n\nBrowsers visiting your server are NOT affected if ANY of these apply:\n- You pass `ApolloServerPluginLandingPageDisabled()` to the `plugins` option of `new ApolloServer`.\n- You pass `ApolloServerPluginLandingPageGraphQLPlayground()` to the `plugins` option of `new ApolloServer`.\n- You pass a custom plugin implementing the `renderLandingPage` hook to the `plugins` option of `new ApolloServer`.\n\nThis issue was introduced in v3.0.0 when the landing page feature was added.\n\n### Patches\nTo avoid this, the sample `curl` command has been removed in release 3.10.1.\n\n### Workarounds\n\nDisabling the landing page removes the possibility of exploit:\n\n```ts\nimport { ApolloServerPluginLandingPageDisabled } from \u0027apollo-server-core\u0027;\n\nnew ApolloServer({\n plugins: [ApolloServerPluginLandingPageDisabled()],\n // ...\n});\n```\n\n### See also\nA similar issue exists in the landing page of Apollo Router. See the corresponding [Apollo Router security advisory](https://github.com/apollographql/router/security/advisories/GHSA-p5q6-hhww-f999).\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [the Apollo Server repository](https://github.com/apollographql/apollo-server/)\n* Email us at [security@apollographql.com](mailto:security@apollographql.com)\n\n### Credits\n\nThis issue was discovered by Adrian Denkiewicz of [Doyensec](https://doyensec.com/research.html).",
"id": "GHSA-2fvv-qxrq-7jq6",
"modified": "2022-08-18T18:55:01Z",
"published": "2022-08-18T18:55:01Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/apollographql/apollo-server/security/advisories/GHSA-2fvv-qxrq-7jq6"
},
{
"type": "WEB",
"url": "https://github.com/apollographql/apollo-server/commit/68a439b6e3af9edc8a2480092f2d49f058be1e64"
},
{
"type": "PACKAGE",
"url": "https://github.com/apollographql/apollo-server"
}
],
"schema_version": "1.4.0",
"severity": [],
"summary": "apollo-server-core vulnerable to URL-based XSS attack affecting IE11 on default landing page"
}
GHSA-2FVW-6H8P-QWR7
Vulnerability from github – Published: 2022-05-24 19:08 – Updated: 2022-05-24 19:08This vulnerability is present in device_graph_page.php script, which is a part of the Advantech R-SeeNet web applications. A specially crafted URL by an attacker and visited by a victim can lead to arbitrary JavaScript code execution.
{
"affected": [],
"aliases": [
"CVE-2021-21803"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-07-16T11:15:00Z",
"severity": "MODERATE"
},
"details": "This vulnerability is present in device_graph_page.php script, which is a part of the Advantech R-SeeNet web applications. A specially crafted URL by an attacker and visited by a victim can lead to arbitrary JavaScript code execution.",
"id": "GHSA-2fvw-6h8p-qwr7",
"modified": "2022-05-24T19:08:18Z",
"published": "2022-05-24T19:08:18Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21803"
},
{
"type": "WEB",
"url": "https://talosintelligence.com/vulnerability_reports/TALOS-2021-1272"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2FWG-QC8C-FRHR
Vulnerability from github – Published: 2022-05-24 19:05 – Updated: 2022-05-24 19:05Trend Micro InterScan Web Security Virtual Appliance version 6.5 was found to have a reflected cross-site scripting (XSS) vulnerability in the product's Captive Portal.
{
"affected": [],
"aliases": [
"CVE-2021-31521"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-06-17T12:15:00Z",
"severity": "MODERATE"
},
"details": "Trend Micro InterScan Web Security Virtual Appliance version 6.5 was found to have a reflected cross-site scripting (XSS) vulnerability in the product\u0027s Captive Portal.",
"id": "GHSA-2fwg-qc8c-frhr",
"modified": "2022-05-24T19:05:38Z",
"published": "2022-05-24T19:05:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-31521"
},
{
"type": "WEB",
"url": "https://success.trendmicro.com/solution/000286452"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-2FWM-M84P-X5QH
Vulnerability from github – Published: 2022-05-14 03:40 – Updated: 2022-05-14 03:40The view review history resource in Atlassian Crucible before version 4.4.3 (the fixed version for 4.4.x) and 4.5.0 allows remote attackers to inject arbitrary HTML or JavaScript via a cross site scripting (XSS) vulnerability through the invited reviewers for a review.
{
"affected": [],
"aliases": [
"CVE-2017-18089"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-02-16T18:29:00Z",
"severity": "MODERATE"
},
"details": "The view review history resource in Atlassian Crucible before version 4.4.3 (the fixed version for 4.4.x) and 4.5.0 allows remote attackers to inject arbitrary HTML or JavaScript via a cross site scripting (XSS) vulnerability through the invited reviewers for a review.",
"id": "GHSA-2fwm-m84p-x5qh",
"modified": "2022-05-14T03:40:06Z",
"published": "2022-05-14T03:40:06Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-18089"
},
{
"type": "WEB",
"url": "https://jira.atlassian.com/browse/CRUC-8169"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/103075"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2FWW-MHH6-5MXR
Vulnerability from github – Published: 2022-05-17 05:44 – Updated: 2025-04-11 03:43Cross-site scripting (XSS) vulnerability in AgentTicketZoom in OTRS 2.4.x before 2.4.9, when RichText is enabled, allows remote attackers to inject arbitrary web script or HTML via JavaScript in an HTML e-mail.
{
"affected": [],
"aliases": [
"CVE-2010-4071"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2011-01-20T19:00:00Z",
"severity": "LOW"
},
"details": "Cross-site scripting (XSS) vulnerability in AgentTicketZoom in OTRS 2.4.x before 2.4.9, when RichText is enabled, allows remote attackers to inject arbitrary web script or HTML via JavaScript in an HTML e-mail.",
"id": "GHSA-2fww-mhh6-5mxr",
"modified": "2025-04-11T03:43:15Z",
"published": "2022-05-17T05:44:05Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2010-4071"
},
{
"type": "WEB",
"url": "http://bugs.gentoo.org/342687"
},
{
"type": "WEB",
"url": "http://lists.opensuse.org/opensuse-security-announce/2010-12/msg00006.html"
},
{
"type": "WEB",
"url": "http://otrs.org/advisory/OSA-2010-03-en"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/41978"
},
{
"type": "WEB",
"url": "http://www.osvdb.org/68882"
},
{
"type": "WEB",
"url": "http://www.vuxml.org/freebsd/96e776c7-e75c-11df-8f26-00151735203a.html"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-2FXF-QJ94-3F83
Vulnerability from github – Published: 2022-08-05 00:00 – Updated: 2022-08-11 15:44A carefully crafted request on XHRHtml2Markup.jsp could trigger an XSS vulnerability on Apache JSPWiki up to and including 2.11.2, which could allow the attacker to execute javascript in the victim's browser and get some sensitive information about the victim. Version 2.11.3 contains a fix for the problem
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.11.2"
},
"package": {
"ecosystem": "Maven",
"name": "org.apache.jspwiki:jspwiki-main"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.11.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2022-27166"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2022-08-11T15:44:49Z",
"nvd_published_at": "2022-08-04T07:15:00Z",
"severity": "MODERATE"
},
"details": "A carefully crafted request on XHRHtml2Markup.jsp could trigger an XSS vulnerability on Apache JSPWiki up to and including 2.11.2, which could allow the attacker to execute javascript in the victim\u0027s browser and get some sensitive information about the victim. Version 2.11.3 contains a fix for the problem",
"id": "GHSA-2fxf-qj94-3f83",
"modified": "2022-08-11T15:44:49Z",
"published": "2022-08-05T00:00:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-27166"
},
{
"type": "PACKAGE",
"url": "https://github.com/apache/jspwiki"
},
{
"type": "WEB",
"url": "https://jspwiki-wiki.apache.org/Wiki.jsp?page=CVE-2022-28732"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Apache JSPWiki XSS due to crafted request on XHRHtml2Markup.jsp"
}
GHSA-2FXJ-Q37F-G6JJ
Vulnerability from github – Published: 2025-07-04 12:30 – Updated: 2025-07-04 12:30Jirafeau normally prevents browser preview for text files due to the possibility that for example SVG and HTML documents could be exploited for cross site scripting. This was done by storing the MIME type of a file and allowing only browser preview for MIME types beginning with image (except for image/svg+xml, see CVE-2022-30110 and CVE-2024-12326), video and audio. However, it was possible to bypass this check by sending a manipulated MIME type containing a comma and an other MIME type like text/html (for example image/png,text/html). Browsers see multiple MIME types and text/html would takes precedence, allowing a possible attacker to do a cross-site scripting attack. The check for MIME types was enhanced to prevent a browser preview when the stored MIME type contains a comma.
{
"affected": [],
"aliases": [
"CVE-2025-7066"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-04T12:15:35Z",
"severity": "MODERATE"
},
"details": "Jirafeau normally prevents browser preview for text files due to the possibility that for example SVG and HTML documents could be exploited for cross site scripting. This was done by storing the MIME type of a file and allowing only browser preview for MIME types beginning with image (except for image/svg+xml, see CVE-2022-30110 and CVE-2024-12326), video and audio. However, it was possible to bypass this check by sending a manipulated MIME type containing a comma and an other MIME type like text/html (for example image/png,text/html). Browsers see multiple MIME types and text/html would takes precedence, allowing a possible attacker to do a cross-site scripting attack. The check for MIME types was enhanced to prevent a browser preview when the stored MIME type contains a comma.",
"id": "GHSA-2fxj-q37f-g6jj",
"modified": "2025-07-04T12:30:27Z",
"published": "2025-07-04T12:30:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-7066"
},
{
"type": "WEB",
"url": "https://gitlab.com/jirafeau/Jirafeau/-/commit/79464ec6276e8eb0e0b0ad597db02b85080d2b63"
},
{
"type": "WEB",
"url": "https://www.cve.org/CVERecord?id=CVE-2022-30110"
},
{
"type": "WEB",
"url": "https://www.cve.org/CVERecord?id=CVE-2024-12326"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2FXW-QWH5-HH6C
Vulnerability from github – Published: 2022-05-14 01:22 – Updated: 2022-05-14 01:22The Contact Form Email plugin before 1.2.66 for WordPress allows wp-admin/admin.php item XSS, related to cp_admin_int_edition.inc.php in the "custom edition area."
{
"affected": [],
"aliases": [
"CVE-2019-9646"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-03-10T22:29:00Z",
"severity": "MODERATE"
},
"details": "The Contact Form Email plugin before 1.2.66 for WordPress allows wp-admin/admin.php item XSS, related to cp_admin_int_edition.inc.php in the \"custom edition area.\"",
"id": "GHSA-2fxw-qwh5-hh6c",
"modified": "2022-05-14T01:22:27Z",
"published": "2022-05-14T01:22:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-9646"
},
{
"type": "WEB",
"url": "https://lists.openwall.net/full-disclosure/2019/02/05/7"
},
{
"type": "WEB",
"url": "https://security-consulting.icu/blog/2019/02/wordpress-contact-form-email-xss-csrf"
},
{
"type": "WEB",
"url": "https://wordpress.org/plugins/contact-form-to-email/#developers"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
Mitigation MIT-4
Strategy: Libraries or Frameworks
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
- Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.
Mitigation
- Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
- For any data that will be output to another web page, especially any data that was received from external inputs, use the appropriate encoding on all non-alphanumeric characters.
- Parts of the same output document may require different encodings, which will vary depending on whether the output is in the:
- etc. Note that HTML Entity Encoding is only appropriate for the HTML body.
- Consult the XSS Prevention Cheat Sheet [REF-724] for more details on the types of encoding and escaping that are needed.
- HTML body
- Element attributes (such as src="XYZ")
- URIs
- JavaScript sections
- Cascading Style Sheets and style property
Mitigation MIT-6
Strategy: Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-27
Strategy: Parameterization
If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.
Mitigation MIT-30.1
Strategy: Output Encoding
- 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.
Mitigation MIT-43
With Struts, write all data from form beans with the bean's filter attribute set to true.
Mitigation MIT-31
Strategy: Attack Surface Reduction
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.
Mitigation MIT-5
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When dynamically constructing web pages, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. All input should be validated and cleansed, 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. It is common to see 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.
- Note that proper output encoding, escaping, and quoting is the most effective solution for preventing XSS, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent XSS, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, in a chat application, the heart emoticon ("<3") would likely pass the validation step, since it is commonly used. However, it cannot be directly inserted into the web page because it contains the "<" character, which would need to be escaped or otherwise handled. In this case, stripping the "<" might reduce the risk of XSS, but it would produce incorrect behavior because the emoticon would not be recorded. This might seem to be a minor inconvenience, but it would be more important in a mathematical forum that wants to represent inequalities.
- Even if you make a mistake in your validation (such as forgetting one out of 100 input fields), appropriate encoding is still likely to protect you from injection-based attacks. As long as it is not done in isolation, input validation is still a useful technique, since it may significantly reduce your attack surface, allow you to detect some attacks, and provide other security benefits that proper encoding does not address.
- Ensure that you perform input validation at well-defined interfaces within the application. This will help protect the application even if a component is reused or moved elsewhere.
Mitigation MIT-21
Strategy: Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-209: XSS Using MIME Type Mismatch
An adversary creates a file with scripting content but where the specified MIME type of the file is such that scripting is not expected. The adversary tricks the victim into accessing a URL that responds with the script file. Some browsers will detect that the specified MIME type of the file does not match the actual type of its content and will automatically switch to using an interpreter for the real content type. If the browser does not invoke script filters before doing this, the adversary's script may run on the target unsanitized, possibly revealing the victim's cookies or executing arbitrary script in their browser.
CAPEC-588: DOM-Based XSS
This type of attack is a form of Cross-Site Scripting (XSS) where a malicious script is inserted into the client-side HTML being parsed by a web browser. Content served by a vulnerable web application includes script code used to manipulate the Document Object Model (DOM). This script code either does not properly validate input, or does not perform proper output encoding, thus creating an opportunity for an adversary to inject a malicious script launch a XSS attack. A key distinction between other XSS attacks and DOM-based attacks is that in other XSS attacks, the malicious script runs when the vulnerable web page is initially loaded, while a DOM-based attack executes sometime after the page loads. Another distinction of DOM-based attacks is that in some cases, the malicious script is never sent to the vulnerable web server at all. An attack like this is guaranteed to bypass any server-side filtering attempts to protect users.
CAPEC-591: Reflected XSS
This type of attack is a form of Cross-Site Scripting (XSS) where a malicious script is "reflected" off a vulnerable web application and then executed by a victim's browser. The process starts with an adversary delivering a malicious script to a victim and convincing the victim to send the script to the vulnerable web application.
CAPEC-592: Stored XSS
An adversary utilizes a form of Cross-site Scripting (XSS) where a malicious script is persistently "stored" within the data storage of a vulnerable web application as valid input.
CAPEC-63: Cross-Site Scripting (XSS)
An adversary embeds malicious scripts in content that will be served to web browsers. The goal of the attack is for the target software, the client-side browser, to execute the script with the users' privilege level. An attack of this type exploits a programs' vulnerabilities that are brought on by allowing remote hosts to execute code and scripts. Web browsers, for example, have some simple security controls in place, but if a remote attacker is allowed to execute scripts (through injecting them in to user-generated content like bulletin boards) then these controls may be bypassed. Further, these attacks are very difficult for an end user to detect.
CAPEC-85: AJAX Footprinting
This attack utilizes the frequent client-server roundtrips in Ajax conversation to scan a system. While Ajax does not open up new vulnerabilities per se, it does optimize them from an attacker point of view. A common first step for an attacker is to footprint the target environment to understand what attacks will work. Since footprinting relies on enumeration, the conversational pattern of rapid, multiple requests and responses that are typical in Ajax applications enable an attacker to look for many vulnerabilities, well-known ports, network locations and so on. The knowledge gained through Ajax fingerprinting can be used to support other attacks, such as XSS.