{"id":"GHSA-89vp-jrxv-24w8","title":"JupyterLab: PyPI extension blocklist package-name canonicalization bypass","summary":"JupyterLab: PyPI extension blocklist package-name canonicalization bypass","severity":"medium","cwe":["CWE-178","CWE-180"],"vendor":"jupyterlab","product":"jupyterlab","ecosystem":"pip","affected":["jupyterlab >= 4.6.0, <= 4.6.1","jupyterlab >= 4.5.0, <= 4.5.9"],"patched":["jupyterlab 4.6.2","jupyterlab 4.5.10"],"published":"2026-07-22","updated":"2026-07-22","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-89vp-jrxv-24w8","references":[{"url":"https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-89vp-jrxv-24w8"},{"url":"https://github.com/jupyterlab/jupyterlab/pull/19184"},{"url":"https://github.com/jupyterlab/jupyterlab/pull/19185"},{"url":"https://github.com/jupyterlab/jupyterlab/pull/19186"},{"url":"https://github.com/jupyterlab/jupyterlab/commit/be9303f5bcd5308eaeae953c5a3c903046682c2c"},{"url":"https://github.com/jupyterlab/jupyterlab/commit/f1beab4a2027af4719d6edc07d52d6cf5a39a432"},{"url":"https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.10"},{"url":"https://github.com/jupyterlab/jupyterlab/releases/tag/v4.6.2"},{"url":"https://github.com/advisories/GHSA-89vp-jrxv-24w8"}],"tags":["ghsa","pip"],"ingestedAt":"2026-07-23T00:08:38.830Z","slug":"GHSA-89vp-jrxv-24w8","body":"## Overview\n\nJupyterLab's PyPI extension manager enforces `blocked_extensions_uris` by comparing the requested install name to blocklist entries with a custom string normalization that is weaker than PyPI package-name canonicalization. An authenticated user can request a PyPI-equivalent spelling such as `JupyterLab.Git` for a blocklisted package such as `jupyterlab-git`; JupyterLab accepts the install request even though pip resolves the variant to the same package.\n\nThis has security implications only for deployments that combine all of the following:\n- an allowlist/blocklist configured with the intent of restricting which packages users can install;\n- the (default) PyPI Extension Manager enabled; and\n- kernels and terminals disabled or delegated to remote hosts (otherwise a user with kernel access can install packages directly regardless of this check) \n\n### Impact\n\nThe vulnerability lets an authenticated user install a package the operator specifically intended to block, defeating the allowlist/blocklist control. Because extensions in principle allow for arbitrary code execution, this vulnerability enables untrusted users to impact the integrity and availability of the jupyter-server instance that was provisioned to them. The user already has access to their own single-user server's data, so installing an extension grants no new read access.\n\nIn particular, the integrity of data can be impacted, and any hardening or restrictions on permitted user actions (download/upload limits) within the single-user server can be circumvented. Availability impact on a JupyterHub deployment is limited: while a user can be expected to exhaust their own kernel pod's resources, this vulnerability makes it easier to also exhaust the single-user server resources or generate more requests to shared resources; where limits are absent, resource exhaustion could potentially degrade the wider deployment.\n\n### Patches\n\nJupyterLab [`v4.6.2`](https://github.com/jupyterlab/jupyterlab/releases/tag/v4.6.2) and [`v4.5.10`](https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.10) contain the patch.\n\nUsers of applications that depend on JupyterLab, such as Notebook v7+, should update `jupyterlab` package too.\n\n### Workarounds\n\nNo action is required for deployments that do not have a custom allow/block list configured. Deployments wanting to disable programmatic extension installation entirely can switch to the read-only extension manager:\n\n```bash\n--LabApp.extension_manager=readonly\n```\n\nor the following traitlet:\n\n```python\nc.LabApp.extension_manager = 'readonly'\n```\n\nYou can confirm that the read-only manager is in use from GUI:\n\n<img width=\"293\" height=\"293\" alt=\"image\" src=\"https://github.com/user-attachments/assets/8016c809-633e-4ed0-a5bc-6bc4793caa0f\" />\n\n## Affected packages\n\n- `jupyterlab >= 4.6.0, <= 4.6.1`\n- `jupyterlab >= 4.5.0, <= 4.5.9`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `jupyterlab 4.6.2`\n- `jupyterlab 4.5.10`","depth":"sunlit","depthScore":28,"depthScoreParts":{"impact":27.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}