CVE-2026-54528 is a high-severity security vulnerability in jupyterlab-git (pip), affecting versions <= 0.53.0. It is fixed in 0.54.0.
Summary jupyterlab-git 0.53.0 (latest, 2026-04-30) uses fnmatch.fnmatchcase() in GitHandler.prepare() (jupyterlabgit/handlers.py:91) to enforce the admin-configured excludedpaths security control. Because fnmatchcase is unconditionally case-sensitive, an authenticated user on a case-insensitive filesystem (macOS APFS, Windows NTFS) can bypass the exclusion by varying the case of the URL path segment, e.g. requesting /git/project/Secrets/... instead of /git/project/secrets/..., gaining read access to git history, file content, and status in directories the administrator explicitly excluded. Vulnerable Code Root Cause fnmatch.fnmatchcase() is unconditionally case-sensitive regardless of the operating system. Contrast with fnmatch.fnmatch() which normalizes via os.path.normcase() on case-insensitive platforms. On macOS APFS and Windows NTFS, /project/Secrets and /project/secrets resolve to the same directory on disk. The exclusion check rejects only the exact-case match, but the downstream url2localpath() resolves the case-varied path to the same filesystem location. Impact An authenticated JupyterLab user with access to the affected Jupyter server can bypass admin-configured excludedpaths by varying the case of the URL path segment. This grants: Read file content at any git ref (/content endpoint) Read working tree files in the excluded directory View git status, log, diff on the excluded path Enumerate commits touching excluded files Attack Scenario Admin configures c.JupyterLabGit.excludedpaths = ["/project/secrets", "/project/secrets/*"] Normal request POST /git/project/secrets/status → HTTP 404 (blocked) Attacker requests POST /git/project/Secrets/status → HTTP 200 (bypass) Attacker reads secret: POST /git/project/Secrets/content with {"filename": "./cred.txt", "reference": {"git": "HEAD"}} → file content returned Exploit See poc.py. Starts a real jupyter-server with jupyterlab-git loaded, configures excluded_paths, and demonstrates bypass + exfiltration via HTTP. <img width="686" height="146" alt="image" src="https://github.com/user-attachments/assets/f5b8d349-539a-44d7-9b17-d13b5f802625" /> Fix Or apply os.path.normcase() to both operands before comparison.
CVE-2026-54528 has a CVSS score of 7.1 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (0.54.0). Upgrading removes the vulnerable code path.
pip
jupyterlab-git (<= 0.53.0)jupyterlab-git → 0.54.0 (pip)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-54528 is reachable in your applications. Explore open-source security for your team.
See if CVE-2026-54528 is reachable in your applications. Get a demo
Upgrade jupyterlab-git to 0.54.0 or later to resolve this vulnerability.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-54528 is a high-severity security vulnerability in jupyterlab-git (pip), affecting versions <= 0.53.0. It is fixed in 0.54.0.
CVE-2026-54528 has a CVSS score of 7.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
jupyterlab-git (pip) versions <= 0.53.0 is affected.
Yes. CVE-2026-54528 is fixed in 0.54.0. Upgrade to this version or later.
Whether CVE-2026-54528 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade jupyterlab-git to 0.54.0 or later.