GHSA-35hp-hqmv-8qg8
Fiber's cache middleware default key generator ignores query string, causing response mix-up across distinct query parameters
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| Go | github.com/gofiber/fiber/v3 | < 3.2.0 | 3.2.0 |
Details
As written in the advisory (Markdown source, shown as plain text).
### Summary
Fiber cache middleware's default key generator uses only `c.Path()` and does not include the query string.
As a result, requests like `/?id=1` and `/?id=2` can map to the same cache key and share the same cached response.
This can cause response mix-up (cache poisoning-like behavior) for endpoints where response content depends on query parameters.
### Details
Default configuration in cache middleware:
- `KeyGenerator: func(c fiber.Ctx) string { return utils.CopyString(c.Path()) }`
References:
- https://github.com/gofiber/fiber/blob/main/middleware/cache/config.go#L90-L92
- https://github.com/gofiber/fiber/blob/main/middleware/cache/cache_test.go#L599-L621
The existing test demonstrates that when handler output depends on query parameter `id`, a second request with a different query still returns the first cached response (cache hit), confirming query is not part of the default cache key.
### PoC
Minimal PoC:
```go
package main
import (
"log"
"github.com/gofiber/fiber/v3"
"github.com/gofiber/fiber/v3/middleware/cache"
)
func main() {
app := fiber.New()
app.Use(cache.New()) // default config
app.Get("/", func(c fiber.Ctx) error {
return c.SendString(c.Query("id", "1"))
})
log.Fatal(app.Listen(":3000"))
}
```
Reproduction:
1. `GET /?id=1`
- Cache miss
- Response body: `1`
2. `GET /?id=2`
- Cache hit
- Response body: `1` (expected `2`)
Local verification command used:
```bash
go test ./middleware/cache -run Test_Cache_WithNoCacheRequestDirective -count=1
```
Observed result: test passes, confirming this is current behavior.
### Impact
- Responses that should vary by query parameters can be mixed between requests.
- In real deployments, this may leak or corrupt user/tenant-specific content if query parameters influence context or data selection.
- This is deployment-dependent but security-relevant, and not safe-by-default for query-variant responses.
### Suggested remediation
- Change default cache key generation to include path + normalized query string (or canonicalized original URL).
- Keep ability for custom key generators.
- Add explicit documentation warning that path-only keying is unsafe for query-dependent responses.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/gofiber/fiber/security/advisories/GHSA-35hp-hqmv-8qg8
- https://nvd.nist.gov/vuln/detail/CVE-2026-30246
- https://github.com/gofiber/fiber/commit/050ff1ff18511c1475b8ec627460216aaecddd4e
- https://github.com/gofiber/fiber/commit/9a0d12c07ed895b84c72987f9288b04137afe5de
- https://github.com/gofiber/fiber
- https://github.com/gofiber/fiber/blob/main/middleware/cache/cache_test.go#L599-L621
- https://github.com/gofiber/fiber/blob/main/middleware/cache/config.go#L90-L92