medium6.5
CVE-2026-31865
Elysia Cookie Value Prototype Pollution
Impact
### Impact Elysia cookie can be overridden by prototype pollution , eg. `__proto__` Sending cookie with the follows name can override cookie value: ```bash __proto__=%7B%22injected%22%3A%22polluted%22%7D ``` ### Patches Patched by 1.4.27 ### Workarounds 1. Use t.Cookie validation to enforce validation value 2. Prevent iterable over cookie if possible
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | elysia | < 1.4.27 | 1.4.27 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Elysiajs | Elysia | before 1.4.27 |