{"schema":"threatline.record/2","record":{"id":"CVE-2026-111058","aliases":["GHSA-rv4m-xm3f-3ccq"],"summary":"Mercury: Unauthenticated Remote Code Execution via /api/kernels","details":"Mercury runs a JupyterLab server with **anonymous access by default** (`mercury_app/__main__.py` sets `--IdentityProvider.token=''` when no `--token`/`MERCURY_TOKEN` is given; when tokenless it also sets `--ServerApp.disable_check_xsrf=True`). It relies on a **blocklist** (`mercury_app/block_handler.py` `BLOCKED_PATTERNS`: `/lab`, `/api/terminals`, `/api/shutdown`, `/files`) to keep anonymous users off dangerous Jupyter endpoints.\n\n## The vulnerability\n`/api/kernels` is **NOT** in the blocklist (and cannot be — Mercury needs kernels to run notebooks), and `patch_kernel_websocket_handler()` (`mercury_app/idle_timeout.py`) only tracks the idle-timeout: it wraps `on_message` to call `self.application._timeout_manager.touch()` and then invokes the original handler with **no filtering of `execute_request`**. So any unauthenticated network client can:\n\n```\nPOST /api/kernels {\"name\":\"python3\"}        -> 201, returns kernel id\nopen websocket /api/kernels/<id>/channels\nsend an execute_request with arbitrary code -> arbitrary Python execution = RCE\n```\n\n## Distinct from GHSA-f8c7-rwf9-fmgm (incomplete fix)\nGHSA-f8c7 was \"Unauthenticated RCE via `/api/terminals`\" — a missing-comma blocklist bypass. Its fix (add the comma so `/api/terminals` is blocked) does **NOT** address `/api/kernels`, which remains exploitable. The blocklist approach is fundamentally unable to cover kernels, so this is not a variant that another blocklist entry fixes.\n\n## Runtime-proven (on the patched version)\nOn **mercury 3.2.4** — the release that fixed GHSA-f8c7 — with the default (tokenless) config, as an unauthenticated client: `POST /api/terminals` returns **403** (the f8c7 fix is present), but `POST /api/kernels` returns **201**; opening the kernel websocket and sending an `execute_request` executed attacker-supplied Python (ran `whoami` as the server process user and wrote a marker file `/tmp/PWNED_MERCURY_RCE`). Full unauthenticated remote code execution. Deterministic PoC (client script + notebook) included.\n\n## Impact\nUnauthenticated, network-reachable arbitrary code execution as the Mercury server process user on every default deployment — complete compromise of the host/container and any data/secrets it can reach. \n\n## Fix\nThe blocklist cannot secure an anonymous kernel-backed server. Require real per-request authentication (a token or password) by default, or restrict the kernel message channel so anonymous websocket clients cannot issue `execute_request` outside Mercury's own controlled execution flow.\n\n## Dedup (3-method)\nOSV.dev CLEAN(0) for `mercury` and `mljar-mercury`; the repo's only advisory (GHSA-f8c7-rwf9-fmgm) covers `/api/terminals` only (description does not mention kernels); no issue/PR describes the `/api/kernels` RCE (#219/#134/#262 are \"add auth\" feature requests that merely confirm anonymous-by-default). Sink independently confirmed on current HEAD (blocklist omits `/api/kernels`; `token=''` default; `patch_kernel_websocket_handler` does no execute filtering).\n\nFinder: Abdullah Kareem (GitHub: CyberKareem).","categories":["Libraries & packages"],"product":"mercury","vendor":"mljar","ecosystem":"pip","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-rv4m-xm3f-3ccq","source_modified_at":"2026-10-19T16:49:08Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"pip","name":"mercury"},"range":"<= 3.2.5"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-111058","source_modified_at":"2026-10-19T17:06:53.899Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"mercury","vendor":"mljar","versions":[{"status":"affected","version":"< 3.2.6"}],"defaultStatus":null},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-rv4m-xm3f-3ccq","source_modified_at":"2026-10-19T17:00:04.132793757Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"mercury","ecosystem":"PyPI","purl":"pkg:pypi/mercury"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.6"}]}],"versions":["1.1.6","1.99.0","1.99.1","1.99.10","1.99.2","1.99.3","1.99.4","1.99.5","1.99.6","1.99.7","1.99.8","1.99.9","2.0.0","2.0.1","2.0.10","2.0.11","2.0.12","2.0.2","2.0.3","2.0.4","2.0.5","2.0.6","2.0.7","2.0.8","2.0.9","2.1.0","2.1.1","2.1.2","2.1.3","2.1.4","2.1.5","2.1.6","2.1.7","2.1.8","2.1.9","2.2.0","2.2.1","2.2.2","2.2.3","2.2.4","2.2.5","2.2.6","2.2.7","2.2.8","2.2.9","2.3.0","2.3.1","2.3.10","2.3.2","2.3.3"]}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-rv4m-xm3f-3ccq","source_modified_at":"2026-10-19T16:49:08Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"pip","name":"mercury"},"version":"3.2.6"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-rv4m-xm3f-3ccq","source_modified_at":"2026-10-19T17:00:04.132793757Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"mercury","ecosystem":"PyPI","purl":"pkg:pypi/mercury"},"version":"3.2.6"}],"cvss":9.8,"severity":"Critical","kev":{"listed":false},"epss":{"probability":0.00437,"percentile":0.37005,"score_date":"2026-10-23"},"published_at":"2026-10-19T16:06:22.646Z","modified_at":"2026-10-19T17:06:53.899Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-rv4m-xm3f-3ccq","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-19T16:49:08Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-111058","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T17:06:53.899Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-rv4m-xm3f-3ccq","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-10-19T17:00:04.132793757Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-111058","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/mljar/mercury/security/advisories/GHSA-rv4m-xm3f-3ccq","tags":["x_refsource_CONFIRM"]},{"source":"CVE List","url":"https://github.com/mljar/mercury/commit/73a40ceb0becf057f495a5738ad7f5a5222a53e1","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/mljar/mercury/releases/tag/3.2.6","tags":["x_refsource_MISC"]},{"url":"https://github.com/advisories/GHSA-rv4m-xm3f-3ccq","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"total","assessed_at":"2026-10-19T17:05:16.440516Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"ecosystem","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T17:06:53.899Z","content_hash":"a25e44dc842c34809b7eb8265345756935d23d2845d967b0e8ca2614fbc79512"}}