# CVE-2026-123301: JetBrains IntelliJ IDEA DOM-based XSS in OpenAPI preview error view

Source: https://junglewise.ai/threats/cve-2026-123301-in-jetbrains-intellij-idea-before-2026-3-dom-based-xss-in-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-06. Updated: 2026-11-06  
License: CC BY 4.0 with a link back

CVE-2026-123301 · Severity: high · CVSS 8.2 · Published 2026-11-06

JetBrains IntelliJ IDEA is a widely-used integrated development environment for creating software applications. A DOM-based cross-site scripting (XSS) vulnerability in the OpenAPI preview error view could allow an attacker to execute arbitrary JavaScript code in the context of a developer's IDE session, potentially leading to theft of authentication tokens, credentials, or source code access.

Technologies: [Jetbrains IntelliJ IDEA](https://junglewise.ai/threats/technologies/intellij-idea). Vendors: [Jetbrains](https://junglewise.ai/threats/vendors/jetbrains).

## Quick answers

**Is CVE-2026-123301 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-123301 being exploited in the wild.

**How severe is CVE-2026-123301?** High severity, with a CVSS score of 8.2, published 6 November 2026.

**Which products and versions are affected?** Jetbrains IntelliJ IDEA before 2026.3.

**Is there a fix for CVE-2026-123301?** Yes: fixed in 2026.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-123301 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-123301?** Check whether you run Jetbrains IntelliJ IDEA at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 2026.3

## Technical details

A DOM-based XSS vulnerability exists in IntelliJ IDEA's OpenAPI preview error view prior to version 2026.3. The vulnerability allows injection of malicious scripts through unsanitized error messages displayed in the OpenAPI preview UI. An attacker could craft a malicious OpenAPI specification file that, when previewed, executes arbitrary JavaScript in the IDE's context.

## Affected products

- JetBrains IntelliJ IDEA before 2026.3

## Timeline

- 2026-11-06: disclosed

## References

- [https://www.jetbrains.com/privacy-security/issues-fixed/](https://www.jetbrains.com/privacy-security/issues-fixed/)

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