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

> Attackers can execute arbitrary JavaScript and potentially code by crafting Git filenames viewed in the JupyterLab Git History tab.

- **Severity:** Critical 9.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 8 Jul 2026
- **Updated:** 9 Jul 2026
- **Also known as:** GHSA-f962-v9hr-pfg5, PYSEC-2026-2540, PYSEC-2026-2541

## What is CVE-2026-54527?

CVE-2026-54527 is a critical cross-site scripting vulnerability in jupyterlab-git, published on 8 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-54527?

8 open source packages ship an affected version, including jupyterlab-git, jupyterlab-git-core and @jupyterlab/git. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `jupyterlab-git` | PyPI | From 0.30.0b3 | 0.54.0 |
| `jupyterlab-git` | PyPI | From 0.30.0b3 | 0.54.0 |
| `jupyterlab-git` | PyPI | From 0.30.0b3 | 0.54.0 |
| `jupyterlab-git-core` | PyPI | From 0.30.0b3 | 0.54.0 |
| `jupyterlab-git-core` | PyPI | From 0.30.0b3 | 0.54.0 |
| `jupyterlab-git-core` | PyPI | From 0.30.0b3 | 0.54.0 |
| `@jupyterlab/git` | npm | From 0.30.0-beta.3 | 0.54.0 |
| `@jupyterlab/git` | npm | From 0.30.0-beta.3 | 0.54.0 |

Products: Jupyter Jupyterlab-Git.

## How do I fix CVE-2026-54527?

Upgrade jupyterlab-git to 0.54.0 or later.

## Is CVE-2026-54527 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54527 exists.

## Other vulnerabilities in jupyterlab-git

- [CVE-2026-54528](https://insights.sbomify.com/CVE-2026-54528/): jupyterlab-git excluded_paths Case-Sensitivity Bypass Allows Reading Excluded Directories (high 7.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54527 and fix it if it is affected.

What it is: CVE-2026-54527 is a critical cross-site scripting vulnerability in jupyterlab-git, published on 8 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54527 exists.

Affected packages and fixed versions:
- jupyterlab-git (PyPI): affected from 0.30.0b3; fixed in 0.54.0
- jupyterlab-git (PyPI): affected from 0.30.0b3; fixed in 0.54.0
- jupyterlab-git (PyPI): affected from 0.30.0b3; fixed in 0.54.0
- jupyterlab-git-core (PyPI): affected from 0.30.0b3; fixed in 0.54.0
- jupyterlab-git-core (PyPI): affected from 0.30.0b3; fixed in 0.54.0
- jupyterlab-git-core (PyPI): affected from 0.30.0b3; fixed in 0.54.0
- @jupyterlab/git (npm): affected from 0.30.0-beta.3; fixed in 0.54.0
- @jupyterlab/git (npm): affected from 0.30.0-beta.3; fixed in 0.54.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54527/ (Markdown: https://insights.sbomify.com/CVE-2026-54527/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54527
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54527
- OSV: https://osv.dev/vulnerability/CVE-2026-54527

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54527/
Summaries are generated and may contain mistakes; the official description above is the record.