CKAN MCP Server is a tool for querying CKAN open data portals. Prior to 0.4.112, canonicalizeParams in src/utils/cache.ts serializes request parameters with unescaped ampersand, equals-sign, and vertical-bar delimiters, allowing different logical parameter sets used by buildCacheKey to collide and an attacker to prime a shared cache with a response for a victim's distinct query. This issue is fixed in version 0.4.112.

Affected: npm: @aborruso/ckan-mcp-server

## Summary

The response cache derives its key from an ambiguous string serialization of the request parameters. `canonicalizeParams` joins sorted `${key}=${value}` pairs with `&` and does not escape `&`, `=`, or the `|` field separators used in `buildCacheKey`. Two **different** logical parameter sets can therefore serialize to the **same** key and share one cache entry. Because the cached value is whatever the upstream returned for whichever request populated the entry first, an attacker can prime a colliding key so a victim's distinct query (same `server_url`) is served the attacker's cached response.

## Affected code

```js // src/utils/cache.ts export function canonicalizeParams(params) { const keys = Object.keys(params).sort(); const pairs = []; for (const key of keys) { const value = params[key]; if (value === undefined || value === null) continue; const serialized = typeof value === "object" ? JSON.stringify(value) : String(value); pairs.push(`${key}=${serialized}`); // value not escaped } return pairs.join("&"); // '&' delimiter, injectable }

export async function buildCacheKey(serverUrl, action, params) { const raw = `${serverUrl}|${action}|${canonicalizeParams(params)}`; // '|' also unescaped return sha1Hex(raw); } ```

Confirmed collisions (identical key):

- `{ q: "budget", rows: 10 }` ≡ `{ q: "budget&rows=10" }` → both canonicalize to `q=budget&rows=10` - `{ filters: { a: "b" } }` ≡ `{ filters:…