CVE-2026-5422
Path Traversal in Jupyter Server 2.17.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-5422 is a high-severity Relative Path Traversal (CWE-23) vulnerability in Jupyter Jupyter Server. Its CVSS base score is 8.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 37th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-33905
Vulnerability Data
A path traversal vulnerability exists in jupyter-server version 2.17.0 due to an incorrect root directory boundary check in the _get_os_path() function within jupyter_server/services/contents/fileio.py. The check uses startswith(root) without appending a trailing path separator, allowing sibling directories with names starting with…
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the same prefix as root_dir to bypass the check. Additionally, the to_os_path() function in utils.py does not strip ".." from path parts, enabling traversal sequences to bypass the vulnerable check. This vulnerability can lead to unauthorized read/write access to files in sibling directories, potentially exposing sensitive data in shared hosting environments.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.3.2
Mitigating Controls (NIST 800-53 r5) AI
Explicit validation of path inputs stops .. sequences from ever being interpreted by the file system.
Access enforcement directly blocks unauthorized file reads/writes that result from unresolved .. sequences.
Information-flow rules can be configured to reject traversals that would move data outside an approved directory boundary.
Least privilege reduces the set of reachable files even when a traversal succeeds.
Secure-engineering principles require safe pathname construction and input neutralization before any file operation.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require input validation and path sanitization that prevent relative traversal.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure development lifecycle mandates input validation and path-handling controls that directly prevent relative path traversal.
Application security requirements explicitly call for controls against path traversal and other injection flaws.
Secure architecture principles include directory isolation and canonicalization, reducing but not eliminating traversal risk.
Secure coding standards require neutralizing path traversal sequences, directly addressing CWE-23.
Security testing in development catches path traversal via static/dynamic analysis, but does not itself implement the fix.
Information access restriction limits which files can be reached, mitigating impact but not preventing the traversal flaw.