GHSA-9X9P-QF8F-MVJG
Vulnerability from github – Published: 2026-05-27 00:28 – Updated: 2026-05-27 00:28Summary
Context.spawn() in liquidjs creates a child Context for the {% render %} tag but does not propagate the parent context's resolved ownPropertyOnly value. The new context re-derives ownPropertyOnly from opts.ownPropertyOnly (the instance-level option), silently discarding any RenderOptions.ownPropertyOnly override that was supplied to parseAndRender(). As a result, a developer who runs a Liquid instance with the backwards-compatible ownPropertyOnly:false and then locks down an untrusted render with parseAndRender(..., { ownPropertyOnly: true }) still leaks prototype-chain properties from inside any {% render %} partial. This is a distinct exploit surface from the previously identified array-filter variants (where, reject, group_by, find, find_index, has) — the underlying root cause in Context.spawn() is shared, but {% render %} is a separately reachable sink that needs no filter usage.
Details
The bug is in Context.spawn():
// src/context/context.ts:105-114
public spawn (scope = {}) {
return new Context(scope, this.opts, {
sync: this.sync,
globals: this.globals,
strictVariables: this.strictVariables
// <-- ownPropertyOnly is missing here
}, {
renderLimit: this.renderLimit,
memoryLimit: this.memoryLimit
})
}
The constructor resolves ownPropertyOnly as:
// src/context/context.ts:47
this.ownPropertyOnly = renderOptions.ownPropertyOnly ?? opts.ownPropertyOnly
Because spawn() passes a RenderOptions object with no ownPropertyOnly, the child context falls back to opts.ownPropertyOnly (the instance-level option), throwing away any per-render override that the parent context had applied. this.opts is the raw normalized instance options object; it is not mutated to reflect render-time overrides.
The {% render %} tag at src/tags/render.ts:51-77 calls spawn() to build the partial's isolated scope:
* render (ctx: Context, emitter: Emitter): Generator<unknown, void, unknown> {
const { liquid, hash } = this
const filepath = (yield renderFilePath(this['file'], ctx, liquid)) as string
assert(filepath, () => `illegal file path "${filepath}"`)
const childCtx = ctx.spawn() // <-- ownPropertyOnly lost here
const scope = childCtx.bottom()
__assign(scope, yield hash.render(ctx))
...
const templates = (yield liquid._parsePartialFile(filepath, childCtx.sync, this['currentFile'])) as Template[]
yield liquid.renderer.renderTemplates(templates, childCtx, emitter)
}
All template variable lookups inside the partial then go through childCtx.readProperty() (src/context/context.ts:123-135), which calls readJSProperty(obj, key, this.ownPropertyOnly). With childCtx.ownPropertyOnly === false (inherited from opts), the protective check at src/context/context.ts:138-141 is skipped and prototype-chain properties are returned to the template:
export function readJSProperty (obj: Scope, key: PropertyKey, ownPropertyOnly: boolean) {
if (ownPropertyOnly && !hasOwnProperty.call(obj, key) && !(obj instanceof Drop)) return undefined
return obj[key]
}
The {% include %} tag is not affected: it does not call spawn(); it pushes onto the parent context's scope stack (src/tags/include.ts:40), so the parent's resolved ownPropertyOnly continues to apply.
Trust model / why this matters: RenderOptions.ownPropertyOnly is documented (src/liquid-options.ts:108-111) as "Same as ownPropertyOnly on LiquidOptions, but only for current render() call". It exists precisely so that developers running a non-strict instance can lock down individual untrusted renders. That contract is broken — the override is silently dropped at every partial boundary.
PoC
mkdir -p /tmp/render-poc
printf '{{ user.passwordHash }}' > /tmp/render-poc/_user.liquid
node -e "
const { Liquid } = require('./dist/liquid.node.js');
const liquid = new Liquid({ ownPropertyOnly: false, root: '/tmp/render-poc' });
class User { constructor(n){ this.name = n; } }
User.prototype.passwordHash = 'bcrypt\$secret';
const u = new User('alice');
liquid.parseAndRender(
'Direct:[{{ user.passwordHash }}] Render:[{% render \"_user.liquid\", user: user %}]',
{ user: u },
{ ownPropertyOnly: true }
).then(console.log);
"
Verified output on liquidjs 10.25.7:
Direct:[] Render:[bcrypt$secret]
The top-level expression {{ user.passwordHash }} is correctly blocked by the per-render ownPropertyOnly:true, but the same expression inside the partial loaded by {% render %} returns the prototype-chain property — proof that Context.spawn() discarded the override.
Impact
- Information disclosure: Any prototype-chain property of objects passed into a
{% render %}partial — including secrets, hashes, internal state, framework-injected helpers — becomes readable from inside the partial template, even when the developer used the documented per-render lockdown. - Realistic threat model: Applications that maintain
ownPropertyOnly:falsefor backwards compatibility (or because their data layer relies on prototype methods) and lock down untrusted-template renders withparseAndRender(..., { ownPropertyOnly:true })are protected at the top level but silently exposed inside any partial. User-controllable template content (CMS snippets, theme partials, email templates) that uses{% render %}becomes an info-leak primitive. - Distinct from existing CVE-2022-25948: the prior advisory only covered direct use of
ownPropertyOnly:false; this is a failure of the documented mitigation (ownPropertyOnly:trueper-render override), not a missing setting. - Distinct from the array-filter variant: same
spawn()root cause, but exploitable without invokingwhere/reject/group_by/find/find_index/has— only requires that the template uses{% render %}(a basic templating feature) and that one of the rendered values has prototype-chain properties.
Recommended Fix
Propagate ownPropertyOnly (and any other security-relevant render options) inside Context.spawn():
// src/context/context.ts
public spawn (scope = {}) {
return new Context(scope, this.opts, {
sync: this.sync,
globals: this.globals,
strictVariables: this.strictVariables,
ownPropertyOnly: this.ownPropertyOnly // <-- propagate resolved per-render value
}, {
renderLimit: this.renderLimit,
memoryLimit: this.memoryLimit
})
}
Passing this.ownPropertyOnly (the resolved value, not this.opts.ownPropertyOnly) ensures any RenderOptions.ownPropertyOnly override flows into spawned child contexts. This single change closes both the {% render %} pathway documented here and the array-filter pathway tracked separately. A regression test should assert that a partial rendered via {% render %} honours parseAndRender(..., { ownPropertyOnly: true }) against an object with prototype-chain properties.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "liquidjs"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "10.25.7"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-44646"
],
"database_specific": {
"cwe_ids": [
"CWE-693"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-27T00:28:06Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Summary\n\n`Context.spawn()` in liquidjs creates a child `Context` for the `{% render %}` tag but does not propagate the parent context\u0027s resolved `ownPropertyOnly` value. The new context re-derives `ownPropertyOnly` from `opts.ownPropertyOnly` (the instance-level option), silently discarding any `RenderOptions.ownPropertyOnly` override that was supplied to `parseAndRender()`. As a result, a developer who runs a Liquid instance with the backwards-compatible `ownPropertyOnly:false` and then locks down an untrusted render with `parseAndRender(..., { ownPropertyOnly: true })` still leaks prototype-chain properties from inside any `{% render %}` partial. This is a distinct exploit surface from the previously identified array-filter variants (`where`, `reject`, `group_by`, `find`, `find_index`, `has`) \u2014 the underlying root cause in `Context.spawn()` is shared, but `{% render %}` is a separately reachable sink that needs no filter usage.\n\n## Details\n\nThe bug is in `Context.spawn()`:\n\n```ts\n// src/context/context.ts:105-114\npublic spawn (scope = {}) {\n return new Context(scope, this.opts, {\n sync: this.sync,\n globals: this.globals,\n strictVariables: this.strictVariables\n // \u003c-- ownPropertyOnly is missing here\n }, {\n renderLimit: this.renderLimit,\n memoryLimit: this.memoryLimit\n })\n}\n```\n\nThe constructor resolves `ownPropertyOnly` as:\n\n```ts\n// src/context/context.ts:47\nthis.ownPropertyOnly = renderOptions.ownPropertyOnly ?? opts.ownPropertyOnly\n```\n\nBecause `spawn()` passes a `RenderOptions` object with no `ownPropertyOnly`, the child context falls back to `opts.ownPropertyOnly` (the instance-level option), throwing away any per-render override that the parent context had applied. `this.opts` is the raw normalized instance options object; it is not mutated to reflect render-time overrides.\n\nThe `{% render %}` tag at `src/tags/render.ts:51-77` calls `spawn()` to build the partial\u0027s isolated scope:\n\n```ts\n* render (ctx: Context, emitter: Emitter): Generator\u003cunknown, void, unknown\u003e {\n const { liquid, hash } = this\n const filepath = (yield renderFilePath(this[\u0027file\u0027], ctx, liquid)) as string\n assert(filepath, () =\u003e `illegal file path \"${filepath}\"`)\n\n const childCtx = ctx.spawn() // \u003c-- ownPropertyOnly lost here\n const scope = childCtx.bottom()\n __assign(scope, yield hash.render(ctx))\n ...\n const templates = (yield liquid._parsePartialFile(filepath, childCtx.sync, this[\u0027currentFile\u0027])) as Template[]\n yield liquid.renderer.renderTemplates(templates, childCtx, emitter)\n}\n```\n\nAll template variable lookups inside the partial then go through `childCtx.readProperty()` (`src/context/context.ts:123-135`), which calls `readJSProperty(obj, key, this.ownPropertyOnly)`. With `childCtx.ownPropertyOnly === false` (inherited from `opts`), the protective check at `src/context/context.ts:138-141` is skipped and prototype-chain properties are returned to the template:\n\n```ts\nexport function readJSProperty (obj: Scope, key: PropertyKey, ownPropertyOnly: boolean) {\n if (ownPropertyOnly \u0026\u0026 !hasOwnProperty.call(obj, key) \u0026\u0026 !(obj instanceof Drop)) return undefined\n return obj[key]\n}\n```\n\nThe `{% include %}` tag is **not** affected: it does not call `spawn()`; it pushes onto the parent context\u0027s scope stack (`src/tags/include.ts:40`), so the parent\u0027s resolved `ownPropertyOnly` continues to apply.\n\nTrust model / why this matters: `RenderOptions.ownPropertyOnly` is documented (`src/liquid-options.ts:108-111`) as \"Same as `ownPropertyOnly` on LiquidOptions, but only for current `render()` call\". It exists precisely so that developers running a non-strict instance can lock down individual untrusted renders. That contract is broken \u2014 the override is silently dropped at every partial boundary.\n\n## PoC\n\n```bash\nmkdir -p /tmp/render-poc\nprintf \u0027{{ user.passwordHash }}\u0027 \u003e /tmp/render-poc/_user.liquid\n\nnode -e \"\nconst { Liquid } = require(\u0027./dist/liquid.node.js\u0027);\nconst liquid = new Liquid({ ownPropertyOnly: false, root: \u0027/tmp/render-poc\u0027 });\n\nclass User { constructor(n){ this.name = n; } }\nUser.prototype.passwordHash = \u0027bcrypt\\$secret\u0027;\nconst u = new User(\u0027alice\u0027);\n\nliquid.parseAndRender(\n \u0027Direct:[{{ user.passwordHash }}] Render:[{% render \\\"_user.liquid\\\", user: user %}]\u0027,\n { user: u },\n { ownPropertyOnly: true }\n).then(console.log);\n\"\n```\n\nVerified output on liquidjs 10.25.7:\n\n```\nDirect:[] Render:[bcrypt$secret]\n```\n\nThe top-level expression `{{ user.passwordHash }}` is correctly blocked by the per-render `ownPropertyOnly:true`, but the same expression inside the partial loaded by `{% render %}` returns the prototype-chain property \u2014 proof that `Context.spawn()` discarded the override.\n\n## Impact\n\n- **Information disclosure**: Any prototype-chain property of objects passed into a `{% render %}` partial \u2014 including secrets, hashes, internal state, framework-injected helpers \u2014 becomes readable from inside the partial template, even when the developer used the documented per-render lockdown.\n- **Realistic threat model**: Applications that maintain `ownPropertyOnly:false` for backwards compatibility (or because their data layer relies on prototype methods) and lock down untrusted-template renders with `parseAndRender(..., { ownPropertyOnly:true })` are protected at the top level but silently exposed inside any partial. User-controllable template content (CMS snippets, theme partials, email templates) that uses `{% render %}` becomes an info-leak primitive.\n- **Distinct from existing CVE-2022-25948**: the prior advisory only covered direct use of `ownPropertyOnly:false`; this is a failure of the documented mitigation (`ownPropertyOnly:true` per-render override), not a missing setting.\n- **Distinct from the array-filter variant**: same `spawn()` root cause, but exploitable without invoking `where/reject/group_by/find/find_index/has` \u2014 only requires that the template uses `{% render %}` (a basic templating feature) and that one of the rendered values has prototype-chain properties.\n\n## Recommended Fix\n\nPropagate `ownPropertyOnly` (and any other security-relevant render options) inside `Context.spawn()`:\n\n```ts\n// src/context/context.ts\npublic spawn (scope = {}) {\n return new Context(scope, this.opts, {\n sync: this.sync,\n globals: this.globals,\n strictVariables: this.strictVariables,\n ownPropertyOnly: this.ownPropertyOnly // \u003c-- propagate resolved per-render value\n }, {\n renderLimit: this.renderLimit,\n memoryLimit: this.memoryLimit\n })\n}\n```\n\nPassing `this.ownPropertyOnly` (the resolved value, not `this.opts.ownPropertyOnly`) ensures any `RenderOptions.ownPropertyOnly` override flows into spawned child contexts. This single change closes both the `{% render %}` pathway documented here and the array-filter pathway tracked separately. A regression test should assert that a partial rendered via `{% render %}` honours `parseAndRender(..., { ownPropertyOnly: true })` against an object with prototype-chain properties.",
"id": "GHSA-9x9p-qf8f-mvjg",
"modified": "2026-05-27T00:28:06Z",
"published": "2026-05-27T00:28:06Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/harttle/liquidjs/security/advisories/GHSA-9x9p-qf8f-mvjg"
},
{
"type": "PACKAGE",
"url": "https://github.com/harttle/liquidjs"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "LiquidJS\u0027s `{% render %}` tag silently bypasses per-render `ownPropertyOnly:true` via `Context.spawn()`"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.