Introduction
A flaw in JetBrains IntelliJ IDEA's built-in web server allows an attacker to read arbitrary local files from a developer's workstation by exploiting improper symbolic link resolution. Given that IntelliJ IDEA is one of the most widely deployed IDEs in enterprise software development, and developer machines frequently hold credentials, private keys, configuration files, and source code, the exposure surface here is significant for any organization with unpatched installations.
The vulnerability, tracked as CVE-2026-41882, carries a CVSS score of 7.4 and was published by JetBrains on April 30, 2026. It affects five distinct release branches spanning from the 2024.3.x line through 2026.1.x, indicating the vulnerable code has been present in the built-in web server component for a considerable period.
Technical Information
Root Cause: CWE-59 and Improper Link Resolution
The vulnerability resides in IntelliJ IDEA's built-in web server, a lightweight HTTP server that runs locally on the developer's machine. This server enables several IDE features including browser-based preview, debugger communication, and REST client functionality.
The root cause is classified under CWE-59 (Improper Link Resolution Before File Access), commonly referred to as "Link Following." This tells us the web server was not properly validating or resolving symbolic links (or equivalent path references) before serving file content. When the built-in web server received a request for a file, it would follow symbolic links without verifying that the resolved target remained within the expected directory scope.
This is a meaningful distinction from classic directory traversal vulnerabilities. CWE-59 specifically concerns situations where a program accesses a file through a name or reference that the program believes is trustworthy, but which actually resolves to an attacker-controlled location, typically via symbolic links or hard links. A simple ../ filter would not catch this class of issue because the path itself may appear well-formed; it is the underlying filesystem resolution that crosses a trust boundary.
Attack Flow
Based on the vulnerability description and the nature of CWE-59, the attack would proceed as follows:
- The attacker identifies that the target is running IntelliJ IDEA with the built-in web server active (this server is enabled by default for many IDE workflows).
- The attacker crafts a request that references a file path which, through symbolic link resolution, points to an arbitrary file on the local filesystem outside the intended serving directory.
- The built-in web server processes the request, follows the symlink or resolves the path reference without proper canonicalization, and serves the content of the target file back to the requester.
- The attacker receives the contents of the arbitrary file, which could include sensitive data such as SSH keys, environment variables, application secrets, or source code.
The specific network exposure requirements and authentication context are not detailed in the public advisory. However, because this is a locally running web server, the attack surface likely involves either local access or the ability to induce the developer's browser to make requests to the local server (for example, via a malicious web page leveraging cross-origin requests).
Relationship to Prior Vulnerabilities
This is not the first time the IntelliJ IDEA built-in web server has been patched for arbitrary file read issues. A previous vulnerability, CVE-2022-46826, addressed a similar file read flaw via path traversal (CWE-35) in version 2022.3. The recurrence under a different CWE suggests the earlier fix handled classic traversal sequences but did not account for link-following attack vectors, which the current patch now closes.
Patch Information
JetBrains has addressed CVE-2026-41882 by releasing patched builds across five supported IntelliJ IDEA release trains, demonstrating the breadth of affected versions and the severity with which the vendor treated this flaw:
| Release Branch | Fixed Version |
|---|---|
| 2024.3.x | 2024.3.7.1 |
| 2025.1.x | 2025.1.7.1 |
| 2025.2.x | 2025.2.6.2 |
| 2025.3.x | 2025.3.4.1 |
| 2026.1.x | 2026.1.1 |
The fix targets the IDE's built-in web server component. Based on the CWE-59 classification, the patch almost certainly adds proper link resolution checks and canonicalization of file paths before the built-in web server reads and serves file content, ensuring that symlinks and equivalent references cannot escape the expected directory scope.
Because IntelliJ IDEA is a closed-source product, no public source code diffs or commits are available. The patch is delivered exclusively through JetBrains' standard update channels:
- The Toolbox App (JetBrains' centralized IDE manager)
- In-IDE update prompts
- Snap packages for Ubuntu users
- Direct download from the JetBrains website
Organizations should map all endpoints by their IntelliJ IDEA release track and roll out the appropriate updates to ensure no branch lags on a vulnerable version. Post-deployment verification should confirm the installed IDE version equals or exceeds the corresponding fixed baseline listed above.
Affected Systems and Versions
The following IntelliJ IDEA versions are vulnerable:
| Product Track | Vulnerable Versions | Fixed Version |
|---|---|---|
| IntelliJ IDEA 2024.3 | All versions before 2024.3.7.1 | 2024.3.7.1 |
| IntelliJ IDEA 2025.1 | All versions before 2025.1.7.1 | 2025.1.7.1 |
| IntelliJ IDEA 2025.2 | All versions before 2025.2.6.2 | 2025.2.6.2 |
| IntelliJ IDEA 2025.3 | All versions before 2025.3.4.1 | 2025.3.4.1 |
| IntelliJ IDEA 2026.1 | All versions before 2026.1.1 | 2026.1.1 |
The vulnerable component is the built-in web server, which is a core feature of IntelliJ IDEA used for browser-based preview, debugger communication, and REST client functionality. Any installation where this server is active (which is the default for many development workflows) is potentially exposed.
Vendor Security History
JetBrains maintains a transparent approach to security disclosure through their centralized "Fixed security issues" page, which documents vulnerabilities across their entire product portfolio. However, the built-in web server in IntelliJ IDEA has a documented pattern of security issues:
| Historical CVE | Description | Severity | Resolved In |
|---|---|---|---|
| CVE-2022-46826 | The built-in web server allowed an arbitrary file to be read by exploiting a path traversal vulnerability | Medium | 2022.3 |
| CVE-2022-46825 | The built-in web server leaked information about open projects | Medium | 2022.3 |
| CVE-2022-48433 | The NTLM hash could leak through an API method used in the built-in web server | Medium | 2023.1 |
The recurrence of file read vulnerabilities in the same component, now under a different CWE classification (CWE-59 versus CWE-35 for the 2022 issue), suggests that earlier remediation efforts addressed specific attack patterns rather than comprehensively hardening the file serving logic. This pattern reinforces the importance of prompt patching whenever new fixes are released for this component.
