GHSA-5xrq-8626-4rwp CVE-2026-47429

When Vitest UI server is listening, arbitrary file can be read and executed

Medium npm

Severity: 9.8 / 10; Medium · CVSS 3.1
Exploit chance (EPSS): 0.88%; Chance of exploitation in the next 30 days. Higher than 59.01% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'); CWE-862 Missing Authorization
Fix: 4.1.0; Upgrade vitest to this version or later

Description

Summary

Arbitrary file can be read on Windows when Vitest UI server is listening, especially when exposed to the network.

Impact

Only users that match either of the following conditions are affected:

explicitly exposes the Vitest UI server to the network (using --api.host or api.host config option)
running the Vitest UI or Browser Mode on Windows

Details

The API handler for /__vitest_attachment__ uses the deprecated isFileServingAllowed incorrectly. https://github.com/vitest-dev/vitest/blob/eb1abf08573032a532015b999ad3501c5e89e3bb/packages/ui/node/index.ts#L77 The function expects the passed value to use cleanUrl after the check before file system related operation. Because of this, it is possible to bypass the check by \\?\\..\\. This is not possible on Linux as Linux errors if a directory named ? does not exist.

A similar problem exists in other places as well.

That said, this isFileServingAllowed check does not actually prevent the API to be abused. Since the API has rerun feature and file write feature, it's possible to run arbitrary script by writing a script as a test file using saveTestFile and running it using rerun. This means exposing the API / Vitest UI is equivalent to giving script execution access. On the browser mode side, there're readFile / writeFile / saveSnapshotFile. So exposing the browser mode is equivalent to giving file read / write access.

PoC

Run Vitest UI
Get the API token by curl http://localhost:51204/__vitest__/
Run curl "http://localhost:51204/__vitest_attachment__?path=C:\\path\\to\\project\\?\\..\\..\\secret.txt&contentType=text/plain&token=$TOKEN" (TOKEN is the API token)
curl shows the content of secret.txt that is outside the project directory

Mitigations

Vitest now ships two configuration flags, allowWrite and allowExec, that gate the privileged operations exploited by this vulnerability. Both are disabled by default whenever the API server is bound to a non-localhost host, ensuring that exposing the server to the network no longer implicitly grants write or execute capabilities to remote clients.

When these flags are disabled, the UI also enters a read-only mode: in-browser code editing and test file execution are turned off, removing the attack surface that allowed remote code execution. Many Browser Mode features are also disabled, like attachments, artifacts or snapshots. See browser.api.

Users who require the full interactive UI on a networked host must explicitly opt in by setting allowWrite and/or allowExec to true.

Affected versions

npm

Package	Vulnerable	Fixed in
vitest	`>= 4.0.0, < 4.1.0`	`4.1.0`
vitest	`< 3.2.6`	`3.2.6`
vitest	`>= 4.0.0, < 4.1.0`	`4.1.0`
vitest	`< 3.2.6`	`3.2.6`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

vitest npm → `4.1.0`

npm

npm install vitest@4.1.0

yarn

yarn add vitest@4.1.0

pnpm

pnpm add vitest@4.1.0

Severity breakdown

CVSS 3.1 9.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Weakness

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

How to prevent it

Implementation: 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 validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
Architecture and Design: 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.
Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked. Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes: realpath() in C getCanonicalPath() in Java GetFullPath() in ASP.NET realpath() or abs_path() in Perl realpath() in PHP
Architecture and Design: 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].
Operation: 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].
Architecture and Design, Operation: Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Architecture and Design: 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. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
Architecture and Design, Operation: Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
Architecture and Design, Operation: Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately. This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Implementation: Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not. In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Operation, Implementation: 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.

CWE-862: Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

How to prevent it

Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.

References

Advisories

Fixes and patches

Packages

github.com/vitest-dev/vitest

Timeline

Jun 1, 2026 Published
Oct 24, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-82fw-gwwq-j7x9 Vitest: Path Traversal / Arbitrary File Read via @vitest/mocker Redirect Mock	Medium	Also affects vitest
GHSA-9crc-q9x8-hgqq Vitest allows Remote Code Execution when accessing a malicious website while Vitest API server is listening	High	Also affects vitest
GHSA-hjqx-j4rw-g7xv zip: Arbitrary file write outside the extraction directory, because ZipArchive::extract validates symlink targets lexically.	High	Same weakness, CWE-22
GHSA-9jrw-8xf7-xqhq Keycloak vulnerable to information disclosure through arbitrary filesystem path probing	Medium	Same weakness, CWE-22
GHSA-4vjg-vx72-qq4g systeminformation has path traversal in Linux networkStats() that allows symlink-based file disclosure outside /sys/class/net	Low	Same weakness, CWE-22
GHSA-m65p-9j7q-6w33 MLflow vulnerable to arbitrary file read on unauthenticated servers via prompt model version source	High	Same weakness, CWE-22
GHSA-g5ff-637f-6q2m LiteLLM: internal_user_viewer arbitrary local file read via `vertex_ai_credentials`	High	Same weakness, CWE-22
CVE-2026-113672 Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes.	Critical	Same weakness, CWE-22

Credits: SaronGrave, jason-anthropic, joevin-slq-docto, koteswar-k, qispark, sapphi-red

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