CVE-2026-39859 — liquidjs
Fix: harttle/liquidjs#870CVE-2026-39859 is a Path Traversal vulnerability in liquidjs. A fix is available for liquidjs — see the affected versions and patch details below.
LiquidJS has a renderFile() / parseFile() bypass configured root and allow arbitrary file read
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-39859.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
liquidjsnpmDescription
liquidjs 10.25.0 documents root as constraining filenames passed to renderFile() and parseFile(), but top-level file loads do not enforce that boundary.
The published npm package [email protected] on Linux 6.17.0 with Node v22.22.1. A Liquid instance configured with an empty temporary directory as root still returned the contents of /etc/hosts when renderFile('/etc/hosts') was called. I have not exhaustively checked older releases yet; 10.25.0 is the latest tested version.
Root cause:
src/parser/parser.ts:83-85callsloader.lookup(file, LookupType.Root, ...)and then reads the returned file.src/fs/loader.ts:38passestype !== LookupType.Rootintocandidates().- For
LookupType.Root,enforceRootis false, sosrc/fs/loader.ts:47-66accepts resolved absolute paths and fallback results without anycontains()check.
This appears adjacent to the March 10, 2026 fix for CVE-2026-30952, which hardened include / render / layout but not the top-level file-loading APIs.
Proof of concept:
const fs = require('fs');
const os = require('os');
const path = require('path');
const { Liquid } = require('liquidjs');
const safeRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'liquidjs-safe-root-'));
const engine = new Liquid({ root: [safeRoot], extname: '.liquid' });
engine.renderFile('/etc/hosts').then(console.log);
Expected result: a path outside root should be rejected.
Actual result: /etc/hosts is rendered successfully.
Impact: any application that treats root as a sandbox boundary and forwards attacker-controlled template names into renderFile() or parseFile() can disclose arbitrary local files readable by the server process.
Suggested fix: apply the same containment checks used for partial/layout lookups to LookupType.Root, and reject absolute or fallback paths unless they remain within an allowed root. A regression test should verify that renderFile('/etc/hosts') fails when root points to an unrelated directory.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | liquidjs | all versions | 10.25.5npm install liquidjs@10.25.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for liquidjs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update liquidjs to 10.25.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-39859 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-39859 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-39859. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-39859 in your dependencies?
O3 Security finds CVE-2026-39859 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.