Eclipse Open VSX up to 1.0.1 HTML File /vscode/unpkg HTML injection

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Eclipse Open VSX up to 1.0.1. This affects an unknown part of the file /vscode/unpkg of the component HTML File Handler. The manipulation leads to HTML injection. This vulnerability is traded as CVE-2026-13323. It is possible to initiate the attack remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Eclipse Open VSX up to 1.0.1. This issue affects an unknown functionality of the file /vscode/unpkg of the component HTML File Handler. The manipulation with an unknown input leads to a html injection vulnerability. Using CWE to declare the problem leads to CWE-79. 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. Impacted is integrity. The summary by CVE is:

In Open VSX Registry before 1.0.2, the /vscode/unpkg/ endpoint serves user-supplied HTML files with Content-Type: text/html and without a Content-Security-Policy or Content-Disposition: attachment response header. An unauthenticated attacker can register a publisher account, upload a VSIX containing a crafted HTML payload, and induce an authenticated user to visit the resulting URL. The browser renders the file inline in the open-vsx.org origin context, enabling session token exfiltration, persistent Personal Access Token (PAT) generation, and unauthorized publication of malicious extension versions. Because Open VSX extensions are distributed to VS Code, VSCodium, Cursor, Windsurf, and compatible editors, a compromised extension update constitutes a supply chain attack against all downstream users.

The advisory is shared at gitlab.eclipse.org. The identification of this vulnerability is CVE-2026-13323 since 06/25/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 1.0.2 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-40945). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Vendor

• Eclipse

Name

• Open VSX

Version

• 1.0.0
• 1.0.1

License

• open-source

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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