Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2026-23939 is a medium-severity Path Traversal (CWE-22) vulnerability in Hex Hexpm. Its CVSS base score is 6.9 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 34th 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.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-23939 is an Improper Limitation of a Pathname to a Restricted Directory vulnerability, classified as CWE-22 (Path Traversal), affecting the hexpm/hexpm project in its Elixir.Hexpm.Store.Local module. The flaw enables relative path traversal and is tied to specific program files like lib/hexpm/store/local.ex and routines such as Elixir.Hexpm.Store.Local:get/3, put/4, delete/2, and delete_many/2. It impacts self-hosted deployments of hexpm that use the Local Storage backend, from commit 931ee0ed46fa89218e0400a4f6e6d15f96406050 up to but not including 5d2ccd2f14f45a63225a73fb5b1c937baf36fdc0. The hex.pm service itself remains unaffected.
Attackers can exploit this vulnerability over the network with low complexity, requiring no privileges, user interaction, or scope changes, as indicated by its CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N). Any unauthenticated remote attacker able to interact with the affected Local Storage backend endpoints could traverse paths to access sensitive files, resulting in high confidentiality impact through unauthorized data disclosure.
Advisories from the CNA at erlef.org, the GitHub security advisory GHSA-42mv-r64p-4869, and the patch commit 5d2ccd2f14f45a63225a73fb5b1c937baf36fdc0 recommend updating self-hosted hexpm deployments to the fixed commit or later versions to mitigate the issue. Additional details are available via OSV.dev at osv.dev/vulnerability/EEF-CVE-2026-23939.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8886
Vulnerability Data
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in hexpm hexpm/hexpm ('Elixir.Hexpm.Store.Local' module) allows Relative Path Traversal. This vulnerability is associated with program files lib/hexpm/store/local.ex and program routines 'Elixir.Hexpm.Store.Local':get/3, 'Elixir.Hexpm.Store.Local':put/4, 'Elixir.Hexpm.Store.Local':delete/2, 'Elixir.Hexpm.Store.Local':delete_many/2. This issue does NOT…
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affect hex.pm the service. Only self-hosted deployments using the Local Storage backend are affected. This issue affects hexpm: from 931ee0ed46fa89218e0400a4f6e6d15f96406050 before 5d2ccd2f14f45a63225a73fb5b1c937baf36fdc0.
- 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
Enforces the intended directory access authorizations that path traversal would otherwise bypass.
Input validation directly neutralizes special path elements before pathname construction occurs.
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.
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.
PR.AA-05 defines and reviews access policies but does not address code-level pathname neutralization, so neither direction prevents CWE-22.
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.
Security testing in development catches path traversal via static/dynamic analysis.
Secure SDLC mandates input validation and path sanitization that directly prevent path traversal.
Application security requirements include rules for safe file handling and canonicalization.
Secure architecture principles require least-privilege file access and directory isolation.
Secure coding standards explicitly forbid unsafe path construction and mandate safe APIs.
Information access restriction limits which files an application may read or write.