CVE-2026-35397: jupyter_server · Path Traversal
Affects jupyter_serverSource CVE Database V5
Not known to be exploited · CVSS 7.6 High : upgrade to 2.18.0 soon.
Data as of 2 Nov 2026, 22:58 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.18.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 5 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 2 Nov 2026.
What to do
Upgrade jupyter_server and jupyter-server to 2.18.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| jupyter-serverjupyter_server | Affected
| Fixed in
|
PyPIjupyter-serverpkg:pypi/jupyter-serverOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available in jupyter_server version 2.18.0 and later; upgrading to this version or newer will remediate the vulnerability. As a temporary workaround, avoid using folder names that overlap or share prefixes to prevent unauthorized access to sibling directories. Check the vendor advisory for the latest remediation guidance.
Description
Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, a path traversal vulnerability in the REST API allows an authenticated user to escape the configured root_dir and access sibling directories whose names begin with the same prefix as the root_dir. For example, with a root_dir named "test", the API permits access to a sibling directory named "testtest" through a crafted request to the /api/contents endpoint using encoded path components. An attacker can read, write, and delete files in affected sibling directories. Multi-tenant deployments using predictable naming schemes are particularly at risk, as a user with a directory named "user1" could access directories for user10 through user19 and beyond. A user who can choose a single-character folder name could gain access to a significant number of sibling directories. Version 2.18.0 contains a fix. As a workaround, ensure folder names do not share a common prefix with any sibling directory.
References
- github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5789-5fc7-67v3 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-35397 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2466858 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-35397.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:43038 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:60520 (opens in a new tab)