# 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.

- **Severity:** Medium 4.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N`)
- **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 available:** No
- **Published:** 1 Jul 2026
- **Updated:** 1 Jul 2026
- **Also known as:** GHSA-f3mc-x4vf-jrw2

## 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 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-13323?

It affects 1 product.


Products: 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.

## 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

- [CVE-2025-6705](https://insights.sbomify.com/CVE-2025-6705/): Privilege escalation in Eclipse Open VSX Registry (high 7.6)
- [CVE-2025-1007](https://insights.sbomify.com/CVE-2025-1007/): Improper Authorization in /user/namespace/{namespace}/details (medium 6.9)
- [CVE-2026-4983](https://insights.sbomify.com/CVE-2026-4983/): Cross-site scripting in Eclipse Open VSX (medium 4.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-13323 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-13323 in the wild and no public exploit code.

Affected product: Eclipse Open VSX. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-13323/ (Markdown: https://insights.sbomify.com/CVE-2026-13323/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-13323
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-13323
- OSV: https://osv.dev/vulnerability/CVE-2026-13323

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-13323/
Summaries are generated and may contain mistakes; the official description above is the record.