An Origin Validation Error in the elysia-cors library thru 1.3.0 allows attackers to…
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and GitHub. Impact type from CWE-346.
Summary
An Origin Validation Error in the elysia-cors library thru 1.3.0 allows attackers to bypass Cross-Origin Resource Sharing (CORS) restrictions. The library incorrectly validates the supplied origin by checking if it is a substring of any domain in the site's CORS policy, rather than performing an exact match. For example, a malicious origin like "notexample.com", "example.common.net" is whitelisted when the site's CORS policy specifies "example.com." This vulnerability enables unauthorized access to user data on sites using the elysia-cors library for CORS validation.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
| — | @elysiajs/cors (npm) | before 1.3.1 | 1.3.1 | Patch available | GHSA-f9qj-4c5x-cpcw |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
- @elysiajs/cors (npm) Vendor— Affected before 1.3.1 Fixed in 1.3.1 Patch available GHSA-f9qj-4c5x-cpcw
Remediation
- Fix · GHSA-f9qj-4c5x-cpcw @elysiajs/cors (npm) Fixed in 1.3.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2025-50864
- 2026-10-03 Alias added: GHSA-f9qj-4c5x-cpcw
References
Other 6
- https://github.com/elysiajs/elysia-cors/blob/main/src/index.ts
- https://github.com/elysiajs/elysia-cors/tree/main
- https://medium.com/@raghavagrawal_23036/cors-bypass-in-popular-opensource-library-ad27fb41e16a
- https://github.com/elysiajs/elysia-cors/commit/9b9eb92e32a7a4b43b6d5108668941701c33e221
- https://github.com/elysiajs/elysia-cors
- http://elysiajs.com
Sources
- CVE-2025-50864 · CVE Program
- CVE-2025-50864 · NVD
- FIRST EPSS
- GHSA-f9qj-4c5x-cpcw · GitHub Advisory Database · CC BY 4.0
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