Jupyter Server open redirect vulnerability

### Impact _What kind of vulnerability is it? Who is impacted?_ Open redirect vulnerability - a maliciously crafted link to a jupyter server could redirect the browser to a different website. All jupyter servers running without a base_url prefix are technically affected, however, these maliciously crafted links can only be reasonably made for known jupyter server hosts. A link to your jupyter server may *appear* safe, but ultimately redirect to a spoofed server on the public internet. This same vulnerability was patched in upstream notebook v5.7.8. ### Patches _Has the problem been patched? What versions should users upgrade to?_ Patched in jupyter_server 1.1.1. If upgrade is not available, a workaround can be to run your server on a url prefix: ``` jupyter server --ServerApp.base_url=/jupyter/ ``` ### References [OWASP page on open redirects](https://cheatsheetseries.owasp.org/cheatsheets/Unvalidated_Redirects_and_Forwards_Cheat_Sheet.html) ### For more information If you have any questions or comments about this advisory, or vulnerabilities to report, please email our security list [security@ipython.org](mailto:security@ipython.org). Credit: Yaniv Nizry from CxSCA group at Checkmarx

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Severity from

GitHub (reviewed advisory)

Weakness

CWE-601

Also known as

CVE-2020-26275, PYSEC-2020-50

• github.com/jupyter-server/jupyter_server/security/advisories/GHSA-9f66-54xg-pc2c
• nvd.nist.gov/vuln/detail/CVE-2020-26275
• github.com/jupyter-server/jupyter_server/commit/85e4abccf6ea9321d29153f73b0bd72ccb3a6bca
• advisory.checkmarx.net/advisory/CX-2020-4291
• github.com/jupyter-server/jupyter_server
• github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2020-346.yaml
• github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2020-50.yaml
• pypi.org/project/jupyter-server