CVE-2026-13323 Cross-site scripting in Eclipse Open VSX
An attacker can inject HTML into the registry to steal tokens and publish malicious extensions, compromising downstream editor users.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-13323?
CVE-2026-13323 is a medium-severity cross-site scripting vulnerability in Eclipse Open VSX, published on 1 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-79
Which versions are affected by CVE-2026-13323?
It affects 1 product.
Products include Eclipse Open Vsx.
How do I fix CVE-2026-13323?
No fix has been published for CVE-2026-13323 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-13323 being exploited?
There is no known exploitation of CVE-2026-13323 in the wild and no public exploit code.
Other vulnerabilities in Eclipse Open VSX
Sources
Also known as GHSA-f3mc-x4vf-jrw2.