CVE-2026-39911 | THREATINT

Description

Hashgraph Guardian through version 3.5.0 contains an unsandboxed JavaScript execution vulnerability in the Custom Logic policy block worker that allows authenticated Standard Registry users to execute arbitrary code by passing user-supplied JavaScript expressions directly to the Node.js Function() constructor without isolation. Attackers can import native Node.js modules to read arbitrary files from the container filesystem, access process environment variables containing sensitive credentials such as RSA private keys, JWT signing keys, and API tokens, and forge valid authentication tokens for any user including administrators.

PUBLISHED Reserved 2026-04-07 | Published 2026-04-09 | Updated 2026-04-09 | Assigner VulnCheck

HIGH: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

HIGH: 8.8CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem types

CWE-668 Exposure of Resource to Wrong Sphere

Product status

Default status

unknown

Any version

affected

Credits

Christ Bouchuen finder

References

github.com/hashgraph/guardian/pull/5929 issue-tracking mitigation

www.vulncheck.com/...an-unsandboxed-javascript-execution-rce third-party-advisory

cve.org (CVE-2026-39911)

nvd.nist.gov (CVE-2026-39911)

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