github.com/lin-snow/ech0 · Ech0's Unauthenticated Like Endpoint Enables Arbitrary Engagement Metric Inflation
Affects github.com/lin-snow/ech0Source GCVE Database
CVSS 5.3 Medium : upgrade to 1.4.8-0.20260503040728-a7e8b8e84bd1 when convenient.
Data as of 27 Oct 2026, 00:07 UTC
- Patch
- Available – fixed in 1.4.8-0.20260503040728-a7e8b8e84bd1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:NWhat to do
Upgrade github.com/lin-snow/ech0 to 1.4.8-0.20260503040728-a7e8b8e84bd1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Gogithub.com/lin-snow/ech0 | Affected
| Fixed in
|
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Description
### Summary **No authentication** is required to invoke **`PUT /api/echo/like/:id`**. The handler is registered on the **public** router group. The service increments **`fav_count`** for the given echo **without** checking identity, **without** a per-user limit, and **without** CSRF tokens. A remote client can **arbitrarily inflate** like metrics with repeated requests. ### Description **Root cause:** The like endpoint is explicitly public (`PublicRouterGroup`). `LikeEcho` in the service layer only runs a repository increment inside a transaction—no viewer/user binding. **Security boundary that fails:** **Integrity** of engagement metrics (likes) and any trust that “likes” represent distinct or authenticated users. **Exploitation:** Discover or guess a public echo UUID (timeline, API, share link) → send **unauthenticated** `PUT` repeatedly → **`fav_count`** increases linearly. ### Affected files | Public route registration | `internal/router/echo.go` | | Like mutation (no auth check) | `internal/service/echo/echo.go` | | Handler | `internal/handler/echo/echo.go` | ### Vulnerable / relevant code **Public PUT route:** ```11:13:Ech0/internal/router/echo.go // Public appRouterGroup.PublicRouterGroup.PUT("/echo/like/:id", h.EchoHandler.LikeEcho()) appRouterGroup.PublicRouterGroup.GET("/tags", h.EchoHandler.GetAllTags()) ``` **Service does not use viewer / rate limit:** ```244:248:Ech0/internal/service/echo/echo.go func (echoService *EchoService) LikeEcho(ctx context.Context, id string) error { return echoService.transactor.Run(ctx, func(txCtx context.Context) error { return echoService.echoRepository.LikeEcho(txCtx, id) }) } ``` ### Execution flow 1. Client resolves `ECHO_ID` (e.g. `GET /api/echo/page` with any valid token, or from UI). 2. Client sends **`PUT /api/echo/like/{ECHO_ID}`** with **no** `Authorization` header. 3. Gin matches **public** route → handler → `EchoService.LikeEcho` → DB increments **`fav_count`**. 4. Repeat N times → count increases by N. ### Proof of concept ```bash BASE="http://127.0.0.1:6277" OWNER_TOKEN=$(curl -sS -X POST "$BASE/api/login" \ -H "Content-Type: application/json" \ -d '{"username":"owner","password":"OwnerPass123"}' | jq -r '.data') ECHO_ID=$(curl -sS "$BASE/api/echo/page?page=1&page_size=1" \ -H "Authorization: Bearer $OWNER_TOKEN" | jq -r '.data.items[0].id') # Single unauthenticated like curl -sS -w "\nHTTP:%{http_code}\n" -X PUT "$BASE/api/echo/like/$ECHO_ID" # Inflate (e.g. 55 times); expect HTTP 200 each time for i in $(seq 1 55); do curl -sS -o /dev/null -w "%{http_code}\n" -X PUT "$BASE/api/echo/like/$ECHO_ID" done # Observe fav_count curl -sS "$BASE/api/echo/$ECHO_ID" | jq '.data | {id, fav_count}' ``` **Observed proof (manual test):** - Each unauthenticated `PUT` returned **HTTP `200`** with success JSON (e.g. `点赞Echo成功`, `code:1`). - **`fav_count`** increased to **113** , demonstrating **linear inflation from one client** with **no authentication**. <img width="1109" height="188" alt="Screenshot 2026-04-01 105522" src="https://github.com/user-attachments/assets/a725cf10-d20b-45a1-95bb-2e8ea396c08c" /> ### Impact **Like counts and ranking/social proof** can be falsified; feeds or “popular” logic tied to `fav_count` are untrustworthy. high-volume loops add DB write load; possible abuse against availability at scale. **Attacker capability:** Anyone on the network can manipulate **public** engagement metrics for any known echo id. Combined with permissive **CORS** browsers could automate cross-origin requests. ## Remediation Require authentication for likes and enforce **one like per principal**, **or** keep anonymous likes but add **rate limiting**, **proof-of-work / captcha**, or **signed tokens** tied to anon sessions; document that counts are **not** auditor-grade metrics.