CVE-2026-90882

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.

Is your site exposed to CVE-2026-90882?

Run a free security scan — no signup, results in seconds.

Weakness Type (CWE)

CWE-942 CWE-942

References

Other References

https://gitlab.eclipse.org/security/cve-assignment/-/work_items/289

Frequently Asked Questions

What is CVE-2026-90882? +

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.

How do I check if I'm vulnerable to CVE-2026-90882? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-46685

RustFS is a distributed object storage system built in Rust. Prior to 1.0.0-beta.2, when RUSTFS_CORS_ALLOWED_ORIGINS is unset, the RustFS S3 …

CVE-2026-8919

Permissive Cross-domain Security Policy with Untrusted Domains in ASUS GameSDK allows a remote user to obtain a local user’s NTLM …

CVE-2024-49763

PlexRipper is a cross-platform media downloader for Plex. PlexRipper’s open CORS policy allows attackers to gain sensitive information from PlexRipper …

CVE-2024-53276

Home-Gallery.org is a self-hosted open-source web gallery to browse personal photos and videos. In 1.15.0 and earlier, an open CORS …

CVE-2024-10315

In Gliffy Online an insecure configuration was discovered in versions before 4.14.0-6. Reported by Alpha Inferno PVT LTD.

CVE-2026-12962

A Permissive Cross-domain Security Policy with Untrusted Domains in Armoury Crate allows a remote user to obtain a local user's …