GHSA-26wg-9xf2-q495: Novu/api Cross-Site Scripting Vulnerability
HIGHGHSA-26wg-9xf2-q495 is a HIGH (CVSS 8.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Novu/api libraries in the npm ecosystem. The issue involves novu has a xss sanitization bypass. Remediation is available by upgrading affected packages to version 3.15.0.
GHSA-26wg-9xf2-q495 at a Glance
Security Impact
CVSS: 8.1
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N).
How to Fix GHSA-26wg-9xf2-q495
To remediate this vulnerability, upgrade all affected Novu/api dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
npm install novu/api@3.15.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls novu/apiHow to Check if You Are Affected
To determine whether your Node.js application is affected by GHSA-26wg-9xf2-q495, inspect your project dependencies using npm:
npm ls novu/apiAnalyze the terminal output to locate any version of Novu/api in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.15.0), your application is affected.
Note: The npm ls novu/api command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where 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. In Novu/api, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
GHSA-26wg-9xf2-q495 Affected Novu/api Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
novu/api
|
npm |
< 3.15.0
|
3.15.0
|
References
Frequently Asked Questions
What is GHSA-26wg-9xf2-q495?
Which Novu/api versions are affected?
What version fixes GHSA-26wg-9xf2-q495?
Is novu/api affected?
What is the CVSS score of GHSA-26wg-9xf2-q495?
What CWE is associated with GHSA-26wg-9xf2-q495?
How can I check npm dependencies for GHSA-26wg-9xf2-q495?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-26wg-9xf2-q495",
"modified" : "2026-04-14T23:23:01Z",
"published" : "2026-04-14T23:23:01Z",
"aliases" : [ ],
"summary" : "Novu has a XSS sanitization bypass",
"details" : "### Summary\n\nXSS sanitization is incomplete, some attributes are missing such as `oncontentvisibilityautostatechange=`. This allows for the email preview to render HTML that executes arbitrary JavaScript,\n\n### Details\n\nSanitization is implemented here:\nhttps://github.com/novuhq/novu/blob/next/libs/application-generic/src/services/sanitize/sanitizer.service.ts\n\nWith `allowedAttributes: false`, all attributes are allowed through `sanitize-html`. Even dangerous ones like `oncontentvisibilityautostatechange=`. The `DANGEROUS_ATTRIBUTES` array tries to handle this by denying more attributes after the fact, but this list is incomplete. I copied all well-known payloads from:\nhttps://portswigger.net/web-security/cross-site-scripting/cheat-sheet\nAnd found that the `oncontentvisibilityautostatechange=` attribute isn't detected. \n\nPS. there seems to also be another even more lax sanitizer here, but I wasn't able to figure out where it is used:\nhttps://github.com/novuhq/novu/blob/next/packages/framework/src/utils/sanitize.utils.ts\n\n### PoC\n\n1. Create a new workflow and add an *Email* step\n2. In the body, write the following HTML code:\n\n```html\n<a oncontentvisibilityautostatechange=\"alert(window.origin)\" style=\"display:block;content-visibility:auto\">\n```\n\n3. Wait a second and notice the XSS popup showing the current origin:\n\n<img width=\"1515\" height=\"610\" alt=\"image\" src=\"https://github.com/user-attachments/assets/7d519a50-3bed-4f04-b78c-9c5938717433\" />\n\nhttps://dashboard.novu.co/env/dev_env_gVtdgDEhgf1CetwX/workflows/onboarding-demo-workflow_wf_gVtdh2uV0h7j3ffK/steps/email-step_st_gVtqdgIrOkYVvP9F/editor\n\n### Impact\n\nThis may look like a Self-XSS similar to https://github.com/novuhq/novu/security/advisories/GHSA-w8vm-jx29-52fr, but it can be more impactful. First of all, if multiple users can access this dashboard, the link above can directly bring the to the email step editor to trigger the XSS.\nAn attacker can also use the Google/GitHub OAuth flows without completing the code callback step, and send that URL to the victim to intentionally log the vicitm into the attacker's account. If the attacker has prepared an XSS payload there, they will now be allowed to view it, so it triggers.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "novu/api"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "3.15.0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/novuhq/novu/security/advisories/GHSA-26wg-9xf2-q495"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/novuhq/novu"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-79" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-04-14T23:23:01Z",
"nvd_published_at" : null
}
}