Cyber Resilience

CVE-2026-39377

Path Traversal in Jupyter Nbconvert 6.5.0 – 7.17.1

Path Traversal
Published
21 April 2026
Modified
23 April 2026
Patch / advisory
View advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
EPSS Score 0.0027 18th percentile
Risk Priority 49 floored blend · peak EPSS

Summary

CVE-2026-39377 is a medium-severity Path Traversal (CWE-22) vulnerability in Jupyter Nbconvert. Its CVSS base score is 6.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 18th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access ControlA06:2025 Insecure Design

EU & UK References

Vulnerability Data

The nbconvert tool, jupyter nbconvert, converts Jupyter notebooks to various other formats via Jinja templates. Versions 6.5 through 7.17.0 allow arbitrary file writes to locations outside the intended output directory when processing notebooks containing crafted cell attachment filenames. The `ExtractAttachmentsPreprocessor`…

more

passes attachment filenames directly to the filesystem without sanitization, enabling path traversal attacks. This vulnerability provides complete control over both the destination path and file extension. Version 7.17.1 contains a patch.

CWE(s)
CWE-22CWE-73

Related Threats

MITRE ATT&CK Enterprise Techniques

T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1083 File and Directory Discovery Discovery
Adversaries may enumerate files and directories or may search in specific locations of a host or network share for certain information within a file system.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1574.007 Path Interception by PATH Environment Variable Stealth
Adversaries may execute their own malicious payloads by hijacking environment variables used to load libraries.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-39378Same product: Jupyter Nbconvert
CVE-2026-35397Same vendor: Jupyter
CVE-2026-25964Shared CWE-22, CWE-73
CVE-2024-9575Shared CWE-22, CWE-73
CVE-2025-54162Shared CWE-22, CWE-73
CVE-2026-40605Shared CWE-22, CWE-73
CVE-2026-31939Shared CWE-22, CWE-73
CVE-2026-34522Shared CWE-22, CWE-73
CVE-2026-30282Shared CWE-22, CWE-73
CVE-2020-1631Shared CWE-22, CWE-73

Affected Assets

jupyter
nbconvert
6.5.0 — 7.17.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V5.3.2

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match

Enforces the intended directory access authorizations that path traversal would otherwise bypass.

SI-10 Information Input Validation good match

Input validation directly neutralizes special path elements before pathname construction occurs.

AC-6 Least Privilege partial match

Least privilege reduces the impact of any unauthorized file access obtained via traversal.

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.

PR.PS-06 full match
prevents

Secure SDLC practices include input validation and path sanitization that eliminate this weakness.

PR.AA-05 mostly match
prevents

Least-privilege file authorization directly limits damage from externally controlled paths.

PR.PS-02 partial match
prevents

Patching/maintenance can remediate known path-traversal flaws in deployed software (partial prevention of exploitability) but does nothing to stop the coding defect from being introduced in the first place.

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.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches path traversal via static/dynamic analysis.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates input validation and path sanitization that directly prevent path traversal.

A.8.26 Application security requirements partial match
prevents

Application security requirements include rules for safe file handling and canonicalization.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles require least-privilege file access and directory isolation.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly forbid unsafe path construction and mandate safe APIs.

A.8.3 Information access restriction partial match
mitigates

Information access restriction limits which files an application may read or write.

References