Vikunja is an open-source self-hosted task management platform. Prior to version 2.2.1, the `DownloadImage` function in `pkg/utils/avatar.go` uses a bare `http.Client{}` with no SSRF protection when downloading user avatar images from the OpenID Connect `picture` claim URL. An attacker who controls their OIDC profile picture URL can force the Vikunja server to make HTTP GET requests to arbitrary internal or cloud metadata endpoints. This bypasses the SSRF protections that are correctly applied to the webhook system. Version 2.2.1 patches the issue.

Affected: Go: code.vikunja.io/api

## Summary

The `DownloadImage` function in `pkg/utils/avatar.go` uses a bare `http.Client{}` with no SSRF protection when downloading user avatar images from the OpenID Connect `picture` claim URL. An attacker who controls their OIDC profile picture URL can force the Vikunja server to make HTTP GET requests to arbitrary internal or cloud metadata endpoints. This bypasses the SSRF protections that are correctly applied to the webhook system.

## Details

When a user authenticates via OpenID Connect, Vikunja extracts the `picture` claim from the ID token or UserInfo endpoint and passes it to `syncUserAvatarFromOpenID`, which calls `utils.DownloadImage` with the attacker-controlled URL:

**Claim extraction** (`pkg/modules/auth/openid/openid.go:70-78`): ```go type claims struct { Email string `json:"email"` Name string `json:"name"` PreferredUsername string `json:"preferred_username"` Nickname string `json:"nickname"` VikunjaGroups []map[string]interface{} `json:"vikunja_groups"` Picture string `json:"picture"` // ... } ```

**Avatar sync trigger** (`pkg/modules/auth/openid/openid.go:348-352`): ```go // Try sync avatar if available err = syncUserAvatarFromOpenID(s, u, cl.Picture) if err != nil { log.Errorf("Error syncing avatar for user %s: %v", u.Username, err) } ```

**Vulnerable download** (`pkg/utils/avatar.go:94-115`): ```…