CVE-2026-86258 nbviewer through 1.0.1 Path Traversal via LocalFileHandler
Attackers can read files from sibling directories outside the configured root in Jupyter nbviewer, disclosing unintended notebooks and credentials.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-86258?
CVE-2026-86258 is a high-severity path traversal vulnerability in jupyter nbviewer, published on 6 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
nbviewer through 1.0.1 contains a path traversal vulnerability in LocalFileHandler.can_show() that uses string-prefix comparison instead of proper path validation. Attackers can read files from sibling directories outside the configured root by requesting paths that share the root as a textual prefix, disclosing unintended notebooks and credentials.
Weakness: CWE-22
Which versions are affected by CVE-2026-86258?
How do I fix CVE-2026-86258?
No fix has been published for CVE-2026-86258 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-86258 being exploited?
There is no known exploitation of CVE-2026-86258 in the wild and no public exploit code.
Sources
Also known as GHSA-v7gx-3h93-r9v6.