{"id":"CVE-2026-42557","aliases":["BIT-jupyter-base-notebook-2026-42557","BIT-jupyter-notebook-2026-42557","BIT-jupyterlab-2026-42557","GHSA-mqcg-5x36-vfcg","PYSEC-2026-2537","PYSEC-2026-2681"],"url":"https://o3.security/vulnerability/CVE-2026-42557","summary":"jupyterlab: Command linker attributes in HTML enable one-click command execution from untrusted content","details":"jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. Prior to 4.5.7, JupyterLab's HTML sanitizer allowlists data-commandlinker-command and data-commandlinker-args on button elements, while CommandLinker listens for all click events on document.body and executes the named command without checking whether the element came from trusted JupyterLab UI. A notebook with a pre-saved HTML cell output containing a deceptive button can trigger arbitrary JupyterLab commands - including arbitrary code execution - on a single user click, without any code being submitted for execution by the user. This vulnerability is fixed in 4.5.7.","published":"2026-05-13T15:06:14.222Z","modified":"2026-08-07T11:51:06.306892755Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"jupyterlab","fixedVersion":"4.5.7"},{"ecosystem":"PyPI","name":"notebook","fixedVersion":"7.5.6"}],"fix":null,"references":[{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42557.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:43038"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-42557"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42557.json"},{"type":"ADVISORY","url":"https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42557"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2477086"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:51:06.306892755Z"}}