CVE-2026-47428
Description
A flaw was found in Vitest, a testing framework. In Vitest Browser Mode, a remote attacker could craft a specific browser-runner URL that, when visited, would allow the execution of arbitrary JavaScript code within the Vitest server. This vulnerability could also lead to the recovery of the VITEST_API_TOKEN, potentially enabling unauthorized authenticated API calls and further compromise of the system.
Statement
Red Hat has assessed this flaw against its shipping products. The vulnerability requires @vitest/browser (Vitest's opt-in Browser Mode) to be installed and actively enabled; it does not affect the core vitest test runner used without Browser Mode. None of Red Hat's shipping products install or execute @vitest/browser, and none configure or enable Browser Mode. Where Vitest is present, it is used strictly as a build/test-time devDependency (core vitest and its non-browser submodules such as expect, runner, snapshot, spy, and utils), not as a shipped runtime component, and several affected streams already ship patched versions (>=4.1.6) or versions below the vulnerable range. Accordingly, while the CVSS score reflects a genuinely severe flaw in Vitest Browser Mode upstream, Red Hat's shipping products are not reachable via this vulnerability.
Mitigation
No mitigation is required for Red Hat shipping products, as the vulnerable @vitest/browser package and Browser Mode feature are not present or enabled in any Red Hat product. Development teams using Vitest as a build/test-time dependency should avoid introducing @vitest/browser or enabling Browser Mode in CI/local environments, and should upgrade to Vitest >=4.1.6 (or >=5.0.0-beta.3 on the 5.x beta line) where Vitest is used, as a matter of general hygiene.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.3 | N/A | 9.6 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | Required |
| Scope | Changed | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Access Control,Confidentiality
Technical Impact: Bypass Protection Mechanism; Read Application Data
The most common attack performed with cross-site scripting involves the disclosure of private information stored in user cookies, such as session information. Typically, a malicious user will craft a client-side script, which -- when parsed by a web browser -- performs some activity on behalf of the victim to an attacker-controlled system (such as sending all site cookies to a given E-mail address). This could be especially dangerous to the site if the victim has administrator privileges to manage that site. This script will be loaded and run by each user visiting the web site. Since the site requesting to run the script has access to the cookies in question, the malicious script does also.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
In some circumstances it may be possible to run arbitrary code on a victim's computer when cross-site scripting is combined with other flaws, for example, "drive-by hacking."
Confidentiality,Integrity,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Read Application Data
The consequence of an XSS attack is the same regardless of whether it is stored or reflected. The difference is in how the payload arrives at the server. XSS can cause a variety of problems for the end user that range in severity from an annoyance to complete account compromise. Some cross-site scripting vulnerabilities can be exploited to manipulate or steal cookies, create requests that can be mistaken for those of a valid user, compromise confidential information, or execute malicious code on the end user systems for a variety of nefarious purposes. Other damaging attacks include the disclosure of end user files, installation of Trojan horse programs, redirecting the user to some other page or site, running "Active X" controls (under Microsoft Internet Explorer) from sites that a user perceives as trustworthy, and modifying presentation of content.
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