# CVE-2026-90882: Reflected arbitrary origins with credentials, allowing cross-origin reads of authenticated user data

> Misconfigured CDN headers allowed cross-origin credential theft and CSRF bypass, enabling attackers to steal user tokens and data.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 22 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-px7g-fw3g-w264

## What is CVE-2026-90882?

CVE-2026-90882 is a high-severity vulnerability in Eclipse Foundation open-vsx.org, published on 22 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

The open-vsx.org deployment returned Access-Control-Allow-Origin reflecting the requesting origin together with Access-Control-Allow-Credentials: true on the authenticated /user/ endpoints. A page on any origin could therefore issue credentialed requests to the service in a logged-in user's browser and read the responses.

This exposed /user (login name, avatar, homepage, tokens URL), /user/tokens, /user/namespaces, /user/extensions, /user/search/{name} and /user/namespace/{name}/members, and — because /user/csrf was readable the same way — allowed the CSRF protection on write endpoints to be defeated. Chaining the two, an attacker page could call /user/token/create and exfiltrate a personal access token carrying publish and delete rights over the victim's namespaces.

The headers were emitted by the CDN/edge layer, not by the application: the Open VSX software sets allowCredentials(true) in exactly one place, against a single exact origin derived from ovsx.webui.url, and defines no CORS mapping on /user/ beyond it. No configuration of the software produces origin reflection with credentials.

Weakness: CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains)

## Which versions are affected by CVE-2026-90882?


## How do I fix CVE-2026-90882?

No fix has been published for CVE-2026-90882 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-90882 being exploited?

There is no known exploitation of CVE-2026-90882 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90882 and fix it if it is affected.

What it is: CVE-2026-90882 is a high-severity vulnerability in Eclipse Foundation open-vsx.org, published on 22 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-90882 in the wild and no public exploit code.

Affected product: Eclipse Foundation open-vsx.org. 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-2026-90882/ (Markdown: https://insights.sbomify.com/CVE-2026-90882/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90882
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90882
- OSV: https://osv.dev/vulnerability/CVE-2026-90882

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-90882/
Summaries are generated and may contain mistakes; the official description above is the record.